James Anderson is to take part in a county 2nd XI match on Tuesday to test his fitness as he bids to play again in the summer's Ashes series. England announced an unchanged squad on Monday for the third Test against Australia at Headlingley, which begins on Thursday. But the focus is on the injured Anderson, England's all-time leading Test wicket-taker, who bowled only four overs in the first Test at Edgbaston before going down with a calf problem. He was sidelined for the drawn second Test at Lord's, which ended on Sunday, but the news he is returning to the field on Tuesday will give hope the 37 year old can return to action. He will step his rehabilitation by playing for Lancashire 2nd XI against Leicestershire in a three-day friendly match in Liverpool. Anderson's fitness will be assessed continually ahead of the fourth Test at his Old Trafford home ground in Manchester, which starts on September 4. England's selectors kept faith with the XI that drew the rain-affected second Ashes Test at Lord's on Sunday, with the hosts having the better of an exciting last day before Australia held out to preserve their 1-0 lead in the five-match series. Surrey left-arm seamer Sam Curran, who did not play at Lord's, retained his place in a 12-man squad for the third Test, which starts at England captain Joe Root's Headingley home ground on Thursday. With just a four-day turnaround between Tests in London and Leeds, major changes were always unlikely. Now England will hope that is sufficient time for World Cup-winning fast bowler Jofra Archer, who took five wickets while repeatedly topping speeds of 90 mph on his Test debut, to recover from the 44 overs he sent down at Lord's. While England's fallible top order remains a concern - World Cup-winning opener Jason Roy has made just 40 runs in four innings this series - the selectors have stuck with what they have at present. They were under less pressure to make changes after the uncapped duo of Dom Sibley and Zak Crawley, considered to be of the best young openers in England, were both out for low scores on Sunday. Sibley got a duck for Warwickshire against Somerset on Sunday and Kent batsman Crawley was dismissed for just five against Essex. England cannot afford to lose in Leeds. A victory for Australia would guarantee they would retain the Ashes, being two ahead with two to play in the five-match series. It is the first time in 10 years that an Ashes Test is being played at Headingley and it has proven to be a happy hunting ground in recent times for the Australians. They have won four of the past five Ashes Tests there, England's lone success coming in 2001.