Andrew Flintoff has made a quicker recovery from a knee operation than expected and reassured England fans that he will be fit for the start of the Ashes series.

The all-rounder revealed that he has suffered no ill-effects from strenuous bowling sessions over the past few days and could return to playing for Lancashire against Durham as early as tomorrow. "I've been bowling pretty much up to full steam and so far, so good," Flintoff said. "I am bang up to where I want to be at this stage and I have had no ill reaction. Not being fit for the Ashes is not an option."

Flintoff, who had surgery on the cartilage in his right right knee six weeks ago, completed his first two full training sessions at Old Trafford on Sunday and did three more over the next two days.

Dr Simon Timson, the ECB’s head of sports science and medicine, visited the player with Mark Young, the England physiotherapist, as part of a “routine” checkup and said he was “pleased” with Flintoff's progress.

Flintoff will travel to Durham but Peter Moores, the Lancashire coach, will leave it until as late as possible before deciding whether to pick him for the LV County Championship match. “It’s gone better than expected," Moores said. "We’re monitoring him on a daily basis, but he looks physically very strong and he’s built up the strength in his right to protect the knee.”

Should he fail to prove his fitness, a place in the team to face Hampshire next Wednesday would present a realistic target. That would give Flintoff the opportunity to play in two four-day matches and four Twenty20 games before the first Ashes Test in Cardiff on July 8. "Come Cardiff, I'll be available," Flintoff said. "For an English cricketer, the Ashes is the biggest thing."

Asked if England could win the series against Australia, Flintoff said: "Of course we can. It's going to be hard. The Australia team has changed a little bit as has England's. We'll be slight underdogs but we have the players who can pull it off."