SPA-FRANCORCHAMPS, Belgium -- The struggling Arrows team turned up for their first Formula One race in a month but with their participation in the Belgian Grand Prix still in doubt.

The team presented two cars for scrutineering at Spa on Thursday, with Brazilian Enrique Bernoldi named as number one driver and German Heinz-Harald Frentzen as the second in a reversal of their usual status.

However Frentzen, who has secured a move to rivals Sauber next year, left the team last month and will not be returning.

"It's not happening. We will not be in Belgium this weekend," said his manager Monte Field. "We've left the team and there will be nothing to bring us to Belgium."

An Arrows source suggested that Frentzen's listing was to satisfy the requirement for two cars to be entered by Thursday's deadline.

Teams are allowed to change their lead driver only once during the course of a season and, with Frentzen out, Bernoldi had to take his place.

But they can change their number two driver twice, leaving the door open for a late replacement for Frentzen some time before Saturday's qualifying, providing race stewards agree.

However the team's participation in the 14th round of the championship, after missing Hungary last month, depends on their completing a deal to sell the team to an unnamed American investor on Friday.

The team did not turn up in Hungary on legal advice, arguing circumstances beyond their control while they negotiated their Formula One survival.

The identity of the purchaser remained a mystery Thursday and former British American Racing (BAR) principal Craig Pollock denied he was involved.

"Absolutely not, it's nothing to do with me," the Scot told Reuters at Spa. "My interest in Arrows is officially finished. That's it."

Pollock, backed by California-based investors, had been deep in talks with Arrows before the team announced the Heads of Agreement had been signed with an interested party.

The team, last in the standings with two points, have not raced since the German Grand Prix at Hockenheim last month and also deliberately failed to qualify for the previous French round.

Bernoldi was present at the circuit but said he did not know who his team mate would be for the weekend.

Arrows also had to pay their engine suppliers Cosworth by a Wednesday deadline but sources at the Ford-owned company saw no problems to prevent the team from racing.