The Finns face a head-to-head showdown with season-long rival Sébastien Loeb. Irrespective of where they finish, whichever driver is the highest on the leaderboard when the rally returns to Cardiff after three days of flat-out driving on gravel tracks in mid- and south Wales will lift the crown.
Team-mates and fellow countrymen Jari-Matti Latvala and Miikka Anttila will provide crucial support in another Focus RS WRC and both pairings have a good record over the Welsh forest roads. Hirvonen won in 2007 while Latvala secured second last season.
All 16 special stages are held on narrow but fast privately-owned gravel tracks, more commonly used by lorries transporting timber. The rally is six weeks earlier than last year and a continuation of the dry and warm autumn in Britain could remove the event's traditionally most difficult challenge – unpredictable weather.
Tree-lined sections high in the hilly forests contrast with wide-open stretches and while ice and snow is highly unlikely in October, fog could be present if the weather worsens. In gloomy conditions it hangs between the trees, while also throwing a white blanket across exposed areas on higher ground.
Hirvonen, who has four wins to his credit this season, remains calm about the challenge ahead. "I feel really excited about the situation and can't wait for the rally to start, but I don't feel any pressure. It will be a hard fight and I don't underestimate the job I need to do. But I have no expectations and because of that I've taken the pressure off myself and put it to one side," he said.
"Although I've won there before, this rally hasn't always been kind to me, but I do enjoy the roads in Wales and know them well. They're fast and flowing, even quicker than my home event in Finland in places. If I had to choose a rally on which to fight for the title then Finland would be my first choice. But Britain would be second on the list. I love driving there and the roads really suit me. At this time of year they won't be covered in ice or snow, so they should be perfect," added 29-year-old Hirvonen.
Latvala has more experience of this rally than his home event in Finland. He began his career in Britain, aged just 17, in 2002 with support from the late Pentti Airikkala and this will be his eighth Rally of Great Britain. "In 2002 and 2003 I drove a lot of rallies in the UK so I'm familiar with the nature of the roads. I've driven all the rally's stages before so that gives me confidence. They're generally fast, especially on Saturday," said the 24-year-old.
"There are straights of up to 2km, but they often end with a hairpin bend and that's difficult if it's foggy. In those situations a driver must have perfect pace notes, because it's impossible to see into the distance and you rely on the notes to pinpoint corners and braking points. A good set of pace notes in the fog can earn a lot of time, but poor notes can be very costly. I will have yellow tinted glasses with me that I also use in the snow. They provide extra definition, so if the weather is bad then they will help me pick out the bends through the fog.
"Up to six drivers can fight for victory on this rally, I really think it could be that wide open. I hope I have the pace to be among them, but a win here for me is less important than helping Mikko to take the title. My main target is to help him achieve that," added Latvala. Â
Abu Dhabi's Khalid Al Qassimi and Michael Orr will drive the team's third Focus RS WRC. Al Qassimi finished 16th last year on his British debut and also gave his full support to Hirvonen's title bid. "The conditions are suited to his driving. A one point lead is small and this is going to be a true test of resilience and consistency for Mikko, but he has a great team behind him and we will all be doing everything possible to make it happen for him," said Al Qassimi.
Team News
* Tyre partner Pirelli will provide BP Ford Abu Dhabi with one regulation tyre pattern. The Scorpion gravel tyre will be available in soft compound only. Teams are not allowed to hand-carve additional cuts into the rubber and each car can carry two spare wheels.
* Six other Focus RS WRCs will start. Henning Solberg / Cato Menkerud and Matthew Wilson / Scott Martin are nominated by the Stobart VK M-Sport squad, which has also entered Steve Perez / Paul Spooner. Private entries have been submitted by Dutch duo Dennis Kuipers / Kees Hagman and Rene Kuipers / Erwin Mombaerts in 2006-specification cars, and Britain's Peter Stephenson and Jim Burns. The rally is also the final round of the Fiesta SportTrophy International series and eight contenders will be in action.
* The team will today (Friday) complete a comprehensive test in northern England in preparation for the rally. Latvala drove on Monday and Tuesday morning in Greystoke Forest, notching up 340km on the first day. Hirvonen took over on Tuesday afternoon at the same location before moving to Kershope Forest for Thursday and a half-day today. The team's preparations will be completed tomorrow (Saturday) when Hirvonen and Lehtinen will pilot a Focus RS WRC in a non-competitive safety car role in the Cambrian Rally in Wales.
Rally Route
The route remains similar to 2008 with the competition split between the forests of mid- and south Wales. However, a new service park will be located in Cardiff Bay and the spectacular indoor test at the city's Millennium Stadium has been dropped. After Thursday's start ceremony in Cardiff, drivers journey 160km north on Friday for two loops of classic tests in mid-Wales, split by a brief 15-minute service in Builth Wells. Saturday is the longest leg and mixes the long Rhondda test in the Vale of Neath, including roads not used since 2003, with the traditional second day tests further north, near Brecon. The final day is based in the south and includes two passes through the famous Walter's Arena section in Rheola Forest. Drivers tackle 16 stages covering 348.30km in a route of 1482.34km.
Q&A with FIA World Rally Championship leader Mikko Hirvonen
How does it feel to be leading the championship with only one round to go?
It feels great but I have led the championship before. I've just not led it with only one event to go! I'm trying not to think about until the rally is over in Cardiff. Hopefully the team will be having a big party though.
Are you feeling under pressure?
Not at the moment, no. It's just really exciting. I actually have a chance to win and I'm keeping my feet firmly on the ground. It will be a hard fight though, I'm not underestimating the job I need to do in Wales. But I have no expectations at all and that way I've taken the pressure away, I've put it on the side. We've had a good feeling for the last six events and I've proved things to myself that I needed to do. That's also taken some of the pressure away.
At what point this year did you feel you could challenge Loeb and take the title?
I started the season thinking I could do it. Then when we retired from Argentina and we scored no points, I virtually gave up. It was only after we won in Greece that I started to hope again. But in Poland after Loeb went off and we moved into the championship lead, I knew we were back in the fight. So Poland was the big turning point in my mind. I always knew it would be difficult though – he's five-times champion!
Has anything changed in your mind since last year?
Nothing has changed. I knew I could challenge him if we had perfect rallies and with one more year of experience and confidence behind us. We've driven some really good rallies this season. Even when he was winning events, we were right behind him in second place. I've challenged him on so many stages and I knew I could do it.
What have you been doing since Spain two weeks ago?
Immediately after the rally I did a passenger ride event for BP and Castrol in Spain. I've been spending some time with my family and done quite a few media interviews and appearances. We've tested in Cumbria this week to find a good set up for Rally GB and I'm feeling comfortable with the car. We're driving in the Cambrian Rally as a course car this weekend. The roads are similar to those we're going to experience in Rally GB, so good experience after the asphalt in Spain. I won the Cambrian back in 2002 so I'm looking forward to going back there.
If you had a choice of any event on which to challenge Loeb, what would it be?
It would have to be Finland. On your home event, you have an added confidence and knowledge of the roads. Rally GB would be definitely be second on the list though. It's a fantastic event and I love driving there. The roads really suit me. They are fast and flowing and at this time of year they won't be covered in ice or snow, so they should be perfect.
Are you concerned at all about starting Rally GB first on the road?
No, not at all. It's not the sort of rally where there is a massive difference between running first, second or third on the road. If it's really muddy then first on the road is the best place to be and if it's dry and dusty then first is also best. So I'm happy with starting first.