Sauber CEO Monisha Kaltenborn says her team is relaxed about its 2013 driver line-up

Sergio Perez has been linked with rival teams after a promising second season in Formula 1, having finished on the podium twice.

The Mexican, who is a member of Ferrari's young-driver scheme, has been tipped as one of the candidates to replace Felipe Massa at the Italian squad, although president Luca di Montezemolo said he lacked experience.

Despite such speculation, Kaltenborn says she is not losing any sleep over the situation with her drivers.

"We make our driver line-up for a whole season, so from that point of view there will be no changes," she told the official Formula 1 website.

"We are not worried. And we are in the middle of a season that hopefully will be a successful one for us - at least all indications point in that direction - and our drivers have to focus solely on this season. Regarding the future, we are not under pressure and I am laid back about it."

Kaltenborn also denied the performance of Kamui Kobayashi has dipped in recent races, saying the Japanese driver has been unlucky.

"I am not sure if it is really the case that his performance is dipping against Sergio. I think that the results do not show the whole picture. Kamui has shown good performances, but yes, he was a bit struck by misfortune.

"Twice in qualifying there were some hiccups with the car - only his car - and on the other hand the very risky strategy Sergio was running on in Malaysia bore fruits and catapulted him into the spotlight.

"So I would say that some factors played for Sergio - and some simply didn't work out for Kamui. But as we still have half the season to go, Kamui can go out and copy Sergio."

The Sauber CEO, whose team is enjoying a strong season, said she rated her drivers' performance in the first half of the year as "satisfactory".

"I would put on record that both show a good development curve. Never forget Kamui is in only his third season, and Sergio only his second.

They have established a good communication line to their engineers and to the whole team, and are always very welcome in the factory as their input is held in high regard.

"I also think that both are behaving well. Of course tempers can sometimes run a little wild, but that's because they are young. So the interim report reads 'satisfactory'."