Havret, whose last European Tour victory was in Scotland at Loch Lomond last year, had an eagle and four birdies at the five par-5s and finished at 11-under 208. He had a bogey at No. 13 and a double-bogey at No. 15.
Wall (65) birdied seven of the last eight holes, including six in a row from the 11th. He's one shot ahead of five players -- Marcel Siem (66), Lee Westwood (66), Ricardo Gonzalez (67), David Howell (68) and Soren Hansen (68), who played despite spraining his wrist on Friday.
Colin Montgomerie appeared to have lost his chance of a Ryder Cup wild card after shooting a 76, falling into a tie for 54th. Oliver Wilson shot a 68 in an effort to clinch the 10th and final automatic spot in the European team. However, he could be surpassed by Nick Dougherty, who shot a 69.
Captain Nick Faldo will announce the European team on Sunday after the tournament.
"I do think I need to win, but it is feasible and it would be a wonderful way to make the team," said Dougherty, who struggled on the greens. "Olly's the favorite, but I'll see if I can make him sweat a little."
Wilson was happy to make the cut, with an eagle and two birdies on the last 10 holes Friday.
"It's going to be a big hunt tomorrow especially with those
Ryder Cup guys doing so well," Havret said.
"It's still a very open tournament but it's always nice to
lead after three rounds."
Montgomerie, who has never lost a singles in his eight Ryder Cup appearances, had little to say after his round.
"I think you've got plenty out of me this week, thank you very much," Montgomerie said.
Darren Clarke shot par 73, including a four-putt, double-bogey 7 at the long 12th. Now in 38th place, Clarke must rely on his second victory of the year at the Dutch Open last week to entice Faldo into awarding him a wild card.