Luke Donald found his touch with the putter to move three clear of Justin Rose with eight holes of the BMW PGA Championship remaining.
The defending champion, set to reclaim the World Number One spot from Rory McIlroy with his display at Wentworth Club, began the day two ahead of his Ryder Cup teammate.
Donald was one over for the day after five holes after missing twice from inside five feet, and Rose caught him with birdies at the third and fourth.
But Donald birdied the sixth, seventh and tenth – the latter from 30 feet – to build a sizeable advantage heading down the home straight.
Scotland’s Paul Lawrie continued his excellent recent form to move into third on nine under.