Dario Franchitti staved off Will Power on a road course, with a time of 1:19.4269s managing to put the Scot just over a tenth of a second faster than the Australian at the end of the Friday afternoon practice session for Sunday's Indy Grand Prix of Sonoma at Infineon Raceway in California.

"There is still room to improve, but I am happy with the performance today," said Franchitti. "It feels like there is some more grip compared to the test here [held last week] and I hope that the track just continues to get better as the weekend progresses."

"We are very close to getting the car where we need it," said a confident Power. "It just comes down to sorting out the fine details. The team will try to think about the changes we can make tonight and see where we can go tomorrow."

Helio Castroneves and Scott Dixon finished third and fourth in the timesheets on the 12-turn 2.52-mile natural-terrain course, meaning that the top four positions were all held by the last four winners at the venue: Will Power is defending champion here, but Franchitti took the honours in 2009, Castroneves in 2008 and Dixon in 2007.

After her big press announcement on Thursday, Danica Patrick - never a natural road course racer - returned to the cockpit with Andretti Autosport and finished the practice session in a disappointing 26th place. Her team mates Ryan Hunter-Reay (12th), Marco Andretti (15th) and Mike Conway (18th) also had a rather average Friday at the races.

"It was a pretty challenging first day for us," admitted Hunter-Reay. "We'll have to change a lot of the settings for Saturday. It was different from last week's test. We felt the car was okay last week. That wasn't the case today. Just overall lack of grip."

A number of drivers struggled particularly with the turn-in to the chicane, culminating with spins for Scott Dixon and then James Hinchcliffe two minutes from the end of the practice session that brought out a full course caution. After race control allowed a brief extension to permit cars one final fast run, a large number of cars then proceeded to run straight off onto the dirt again before returning to pit road.

Alex Tagliani had earlier caused a full course caution, a little over nine minutes from the end of the initial 45-minute part of the 75-minute Friday practice reserved for rookies and drivers outside the top ten. He was uninjured after running off at speed into the tyre barrier out of turn 3.

The session saw current Renault Formula 1 test driver Ho-Pin Tung take to the track with Dragon Racing and finish the day with a very creditable 17th position. Tung was reunited with Dragon after he impressed them at Indianapolis in May, and the team struck a technical support deal with Sam Schmidt Motorsports to run him this weekend on the California road course under the Schmidt Dragon Racing banner - which should see him become the first Chinese driver to make an IndyCar Series start.

Also appearing in the session was Simon Pagenaud, the current 'super sub' of IndyCar, today finishing in 25th place after stepping in at short notice for HVM's Simona de Silvestro. She had fallen foul of US immigration problems with her visa when she tried to return to the States from a trip to her native Switzerland. Pagenaud had to fly in from Peugeot sportscar duties in Spain to caretake the #78 until de Silvestro hopefully makes it to Sonoma, the Frenchman having previously substituted for Justin Wilson and Ana Beatriz at Dreyer & Reinbold earlier in the season.

"It's unfortunate what happened to Simona and you obviously never wish to have this situation," said Pagenaud. "As everybody knows I want to be in IndyCar next year so when an opportunity like this comes up to drive the car for HVM, it's an opportunity I really need, especially with a good team like this one ... It's my job and what I love to do."

Further up pit lane, it was former Jordan F1 driver and GP2 champion Giorgio Pantano's turn to stand in for Wilson this week and he will also take the #22 into next week's maiden Baltimore street race. Pantano impressed in his first IndyCar outing since 2005, and was in fifth place behind the top series regulars at the end of the 75 minutes, but he has even bigger plans for Saturday.

"We are okay, but I'm sure there's a lot we can do, a lot we can gain from what we did today," he said. "We just need to check the data and work with the engineers to see where we can find more overall grip. I'm sure tomorrow we will be closer to where we want to be."

Just behind Pantano in sixth place was another road course specialist, Sebastien Bourdais, who was back in the #19 for Dale Coyne Racing. His team mate James Jakes - who has had a difficult season after being thrown into IndyCar at very short notice - had one of his best days of the year with a strong tenth place in the session timesheets.

Fellow Brit Martin Plowman returned for his second outing with the rejuvenated AFS/Sam Schmidt Motorsports outfit, and was in 20th position as the session concluded.

Full practice times and positions available.