Speculation is mounting within the F1 paddock that veteran returnee Pedro de la Rosa could be eased out of Sauber to make way for one of two well-backed GP2 Series front-runners as early as next month's Turkish Grand Prix in Istanbul.

Despite having begun the campaign with the upper hand over 'rookie' team-mate Kamui Kobayashi - admittedly, to the surprise of many observers - de la Rosa has since been out-qualified by the highly-rated young Japanese ace in both Malaysia and China.

There are seemingly concerns at Hinwil that the Spaniard is taking rather longer to re-acclimatise to top flight competition than had been hoped following three years away from the grand prix grid, and that his development skills expertly honed by many years spent testing for multiple world champions McLaren-Mercedes are not helping to progress the C29 as quickly as had been anticipated.

With the knives already out for the Barcelona native, it has been reported that both Pastor Maldonado and Luca Filippi are under consideration to replace him. The Italian - a three-time race-winner from four seasons in the feeder GP2 category - has tested for Minardi, Honda and Super Aguri in the past and was reputedly able to bring with him some EUR10 million in sponsorship when he was vying for a race seat with the latter at the end of 2007.

"It would be a dream," the 24-year-old told French magazine Auto Hebdo, "but I prefer to concentrate on (new series) Auto GP."

de la Rosa, meanwhile, is bidding for a significant step forward at his home grand prix around the Circuit de Catalunya next weekend, having not only struggled to make much of an impression pace-wise thus far in F1 2010, but having also only seen the chequered flag on a single occasion - with a distant twelfth place Down Under in Melbourne the Swiss outfit's sole finish to-date.

Since the Chinese Grand Prix just over a week ago, engine-supplier Ferrari is understood to have identified a general issue with the pneumatic system of its 2.4-litre V8 powerplant - which let both drivers down in Malaysia, in the frustrated de la Rosa's case before the race had even got underway.

"[In Shanghai] we had different sensors and the pneumatic system failed for some other reason," explained the 39-year-old, speaking to Spanish publication El Mundo Deportivo. "We hope that Ferrari have now solved the engine problem, and we have high hopes for Barcelona. We have new parts to improve the car's performance - it is a major leap."

A key factor - quite literally - in Sauber's renaissance, de la Rosa opines, will be the recent arrival at the former BMW operation of ex-Force India technical director James Key, in-place of departing team stalwart Willy Rampf. The Catalan clearly expects great things of the Englishman.

"I think he is the right man for the job," he reasoned, "and already during the [Chinese Grand Prix] weekend we realised that he knows what he is talking about. He now knows what are our weak points and will work on them.

"In this business, it's always good to have fresh ideas from people who have worked in different environments and with different cars. It's important to have new people from time-to-time. If you look at a top team, every year or two they get new people from other teams."