Defending his IndyCar championship appears the last thing on Will Power’s mind going into this weekend’s season finale.

The Australian heads into the double-points Grand Prix of Sonoma in California still in with a shot of retaining the crown he won for the first time last year.

Power is one of six drivers who can mathematically claim the championship in the 85-lap street circuit race, but the death of Justin Wilson has cast a pall on the entire weekend.

Wilson died earlier in the week after suffering severe head injuries during the second last race of the season at Pocono in Pennsylvania.

The Englishman’s head was struck by debris from another car in an accident which has left many, including Power, deeply affected.

“The Verizon IndyCar Series is going into Sonoma with heavy hearts this weekend,” Power said.

“I had the pleasure – and I do mean pleasure – to race against Justin Wilson for many years in this series.

“To see how hard he worked was an inspiration to many people in the paddock. Justin was a great driver – a winning driver – but more than that, he was just a fantastic human being. There is no other way to put it.”

Power said his wife Liz had worked with Wilson and the popular driver’s death had hit both of them particularly hard.

“No one had a bad thing to say about Justin – no one. He will be sorely missed,” he said.

Power heads into the weekend fourth on the championship standings, 61 points behind teammate and ex-Formula One star Juan Pablo Montoya.

Power has three wins and four poles from his previous five trips to Sonoma and is one of only two drivers with more than one race win at the venue.

Montoya will claim the championship if he finishes first or second this weekend, or if he crosses third and second-placed Graham Rahal doesn’t win the race.

Power will simply have to hope for the best if he can claim a maximum haul of 104 points, with Montoya, Rahal and Scott Dixon all ahead of him in the standings.