BMW's Nick Heidfeld believes Formula One's return to Europe at Imola this week could force a re-writing of the early-season form book.

"We can expect many teams to arrive for the start of the European season with revised cars, which might well bring about another shift in the balance of power," the German driver said.

"We'll be lining up with a modified rear section and a new front wing," he said. "Indeed, we had already introduced new aerodynamic elements for the race in Australia and the improvement was noticeable straightaway.

"Our aim is to make aerodynamic modifications of varying degrees before each Grand Prix."

Heidfeld finished fourth in the April 2 Australian Grand Prix, with Jacques Villeneuve a strong sixth, to send the new BMW Sauber team fifth in the championship.

Boston Marathon

Olympic silver medallist Meb Keflezighi poses the biggest threat to 2005 winner Hailu Negussie in an expected Boston Marathon showdown today between American and African runners.

Keflezighi heads a strong American contingent taking on Ethiopian Negussie and previous champions Robert Cheruiyot and Timothy Cherigat from Kenya.

Keflezighi, 30, ranked as America's top marathon runner in 2005 by Track & Field News, is entering his first-ever Boston race.

Some say he could run away with the $100,000 top prize. Americans Alan Culpepper, whose fourth place in Boston last year marked the highest finish for a US runner since 1987, Brian Sell and Clint Verran round out an elite US team.