Robert Kubica has admitted that Michael Schumacher's peers were expecting him to perform better than he has so far on his return to Formula 1.
The seven-time world champion has been outqualified and outraced by team-mate Nico Rosberg over the first four grands prix of the season and, although Kubica expects him to challenge at the front before long, he believes Schumacher is having a difficult time.
"We are all surprised that he is struggling, but it shows that he is a human being," said Kubica.
"I know from the past, although I haven't won seven world championships, that if you are struggling, everything becomes quite difficult. But when you put the puzzles and all the small things together, everything becomes much easier and you are back to the pace you are expecting.
"I think everybody was expecting Michael to be right there on the top. It hasn't been the case in the beginning but it's not so simple as it might look. It's a good example that it's not so easy as it looks to drive a Formula 1 car, it's very complex."
But Kubica played down suggestions that people should re-evaluate their opinions of Schumacher.
"As a driver, you realise a bit more how complex F1 is," he added. "I never felt Schumacher could win a race with Minardi because I know how difficult things are, and how important things outside of yourself, like the car and the team, are to the final result.
"For me it's difficult to judge, I'm not driving the car and I'm not inside that team. Some drivers like this, some like that. I was one of the drivers that had to change completely the style and set-up preferences for the new tyres, so it's a difficulty that maybe Michael is going through."