SPA-FRANCORCHAMPS, Belgium -- Kimi Raikkonen has pulled a muscle ahead of the Belgian Grand Prix this weekend, forcing Alfa Romeo reserve driver Marcus Ericsson to miss an IndyCar race after being placed on standby.

On Thursday morning, the Schmidt Peterson IndyCar team confirmed American driver Conor Daly will stand in for Ericsson for this weekend's race at Portland. Ericsson is competing in his rookie IndyCar season after being replaced by Alfa Romeo at the end of last year -- he was kept on as a back-up driver.

Raikkonen was reported to have limped into the Spa-Francorchamps paddock ahead of the day allocated for media commitments. The Finn played down his chances of missing the race with a typically frank set of exchanges to the media.

When asked what he had done, he said: "I pulled a muscle and that's about it. We will see what happens."

On how he had done it, he said: "Sport. Injuries. Getting old."

Pressed on which leg he had injured, the 2007 world champion replied: "One of those. Left."

He was also asked about whether the injury would impact his ability to brake, to which he smiled and said: "Better the brake than the throttle! It should be OK.

"Honestly if it wouldn't be, I wouldn't even try."

Raikkonen went on to stress that he was fully committed to racing at the weekend.

"If you want to put that it's not 100 percent, you can put whatever number you like. Obviously it's impossible to try, we have simulators and that doesn't tell an awful lot anyway so we will see how it is. In my head it should be fine but you never know.

"Obviously we need to have some back up plans. It would be stupid not to have our third driver in case I couldn't be driving in the worst-case scenario.

"There's a reason why the team has a third driver if something happens. I think it's a normal story. It's a difficult situation for him also, because he had a race, but that's how it is."

Raikkonen is known to like an alcoholic drink away from the race track -- in his recently-released autobiography, the Finn detailed a 12-day drinking bender during a big gap between races earlier in his career. He finished his media session on Thursday by making light of that.

"Drinking is probably more safe than sport. You don't get injured, only hungover!"