By Alan Baldwin

LONDON (Reuters) - Brazilian Bruno Senna will race for Renault in this weekend's Belgian Grand Prix instead of Germany's Nick Heidfeld, the Formula One team said Wednesday.

Senna, nephew of the late triple world champion Ayrton, raced for struggling Spanish-based team Hispania (HRT) without scoring a point last year and is currently a Renault test and reserve driver.

Speculation about the 27-year-old possibly replacing Heidfeld has been bubbling away since the Hungarian Grand Prix, where Renault team boss Eric Boullier was critical of the veteran's performances.

Boullier said in Budapest that Heidfeld's performances were 'good, but not good enough'.

The team's Luxembourg-based owners Genii Capital also recently trumpeted a new joint venture in Brazil with the WWI Group to manage an investment portfolio totaling $10 billion.

Renault said in a statement that Senna would partner Russian Vitaly Petrov at Spa-Francorchamps but gave few details beyond that.

"Bruno will attend the Official FIA Press Conference tomorrow at 15.00," the team added. "A press release with further details on the matter will be issued tomorrow morning."

Senna took part in Friday practice for Renault in Hungary, replacing Heidfeld, and also drove the team's 2009 car at a private test in Spain during the August break.

Heidfeld was drafted in as a replacement for Robert Kubica before the start of the season when the Pole suffered a life-threatening rally accident that he is still recovering from.

As an experienced driver with more than 180 races under his belt, compared to Petrov's single season in the sport, the German had been expected to take the senior role at the team in a competitive car.

The German has scored more points than his team mate -- 34 to the Russian's 32 from 11 races -- and was on the podium in Malaysia in the season's second round -- but Renault clearly expected more from him.

Former team boss Eddie Jordan, now a pundit for BBC television, said Monday that Heidfeld -- who once drove for him -- would be dropped and hinted at 'funding shortages' at the team, which Renault have denied.

"While Heidfeld is on a salary, Senna, Renault's reserve driver, comes with several million pounds of sponsorship," said the Irishman.

(Reporting by Alan Baldwin, editing by John Mehaffey; For Reuters sports blog Left Field go to: http://blogs.reuters.com/sport)