Fernando Alonso admitted on Thursday that he was surprised how long it had taken him to recover from his high-speed accident at the season-opening Australian Grand Prix.
Alonso suffered rib and chest injuries when he crashed in Melbourne in March and was forced to miss the Bahrain Grand Prix where Stoffel Vandoorne replaced him.
"I am perfectly okay now," he said on Thursday, ahead of this weekend's Russian Grand Prix. "I have been working and training okay.
"In the last two weeks, probably after China, (I had) another four or five days with some strange feelings, but for the last 10 days it was perfectly ok.
"It took a little bit longer than I thought or what I anticipated, it was around 42-43 days from Melbourne to be 100 percent, but it is probably normal."
The two-time world champion Spaniard, who has yet to emulate his Belgian deputy's achievement in scoring a point for the Honda-powered McLaren team this season, said he felt the Russian race would be a good test of their progress.
"We are definitely more competitive, race after race, but here is a good test for us -- the power effect is quite high here.
"I think it is the fourth-highest of the championship, so we will need to recover in the corners big-time..."
He added that the difference between last year's disappointing performances and this season's improved form was very clear.
"It's night and day," he said. "This year is a completely different picture and we are able to fight with other cars.
"China is not a good example because of the different strategies -- and the different tyre combinations and tyre ages that we ran there makes the overtaking very easy on both sides."