CHRIS Walker's run of misfortune continued in the first race of round six of the Superbike World Championship at Silverstone when an engine problem caused him to crash out - team-mate Troy Corser clinched a creditable seventh place in the first race and ninth in the second.

Walker went into the first race nursing damaged ribs but both he and Corser got off to a flying start.

The Foggy Petronas Racing riders were neck and neck in the early stages of the opening race after Walker, suffering from three broken ribs following a crash in practice, had stormed from 13th on the grid to seventh place by the end of the first lap.

But the engine failure caused Walker's bike to lock up in a low-side crash, in which he suffered no further injury.

Corser found himself in the unusual position being held up by the factory Ducati bike of James Toseland, the championship leader, but was powerless to resist the challenge of a host of other Ducatis through the faster sections of the circuit. When Toseland crashed out, Corser was able to improve his lap times.

Corser said: "I didn't get a bad start and went round the outside of everyone round turn one. Then James was slowing me up in all the corners and at one point I almost went off the track when I tried to take him round the outside.

"But I couldn't get past him in the slower sections and he would always pull away down the straights. That allowed the likes of Martin and McCoy to catch me and come past on the straights but, after James crashed, I was running the same lap times as them and I think I could have stayed with them. But I was reasonably happy with seventh."

Walker said: "I got a really good start and got up to where I should have been on the grid.

"I was right behind Troy when the bike locked up and low sided. Obviously I'm more than disappointed."

Noriyuki Haga secured his third win of the season in a thrilling last lap, when he dived under Chris Vermeulen in the penultimate corner.

An audacious last-lap manoeuvre from the Renegade Ducati rider saw him dip inside the Ten Kate Honda rider as they entered the slow Woodcote chicane to steal victory just yards from the chequered flag.

And Pierfrancesco Chili, on the PSG-1 Corse Ducati, placed third after having advanced from the back of the grid following an engine blow-up which had ruined the 39-year-old veteran campaigner's superpole qualification lap.

Vermeulen reversed the order in the second race as he this time held off the challenge on the Japanese star.

Ducati Fila's Regis Laconi believes he can look forward to the next round of the World Superbike Championships at Laguna Seca with optimism, despite having suffered mixed fortunes at Silverstone.

Laconi had crashed out of the first race but the Frenchman claimed third position on the podium, a result good enough to secure first place in the overall standings after amassing 171 points.