Timo Glock believes Marussia's biggest obstacle this season could be their all-rookie line-up.
Having parted ways with the experienced German due to financial reasons, Marussia sold Glock's seat to Luiz Razia, who joins Max Chilton in the only all-rookie driver pairing on this season's grid.
"It's definitely not going to be easy for them, especially in testing, where you need to be able to make the right decisions in pinpointing the weaknesses of the car," Glock told Autosport.
"That's something that only comes from experience.
"There's a lot of pressure on Luiz and Max to get up to speed with the car quickly.
"That's the critical part; knowing that perhaps the simulation you have brought to a track isn't quite accurate and being able to make a forward step from there."
Glock, though, holds no grudges against the team, saying he understands the need to secure the team's financial future.
"Generally they just need to find a way of getting more financial support so that they can move forwards and develop.
"The bigger teams won't stop developing and that's what makes it so hard for the smaller teams to catch up. The bigger teams bring updates to every race while the smaller teams have updates maybe every five or six races.
"At least they've definitely moved forward with the car. It's quicker this year. It's all about developing, about how they get on with KERS."