Shane Warne is having no trouble staying in shape at age 37 © Getty Images

Shane Warne has defended his Test team-mates against age-related problems and says Glenn McGrath should not be written off ahead of the Ashes. Australia's older batsmen have been targeted by Dennis Lillee as concerns ahead of the summer while Geoff Lawson and Ian Chappell have questioned McGrath's future after his slow comeback during the Champions Trophy.

"The age only comes into it if you are not performing," Warne, who is 37, was reported by AFP. "We've performed pretty well, this group of players, for a period of time. Since the Ashes we've won 11 out of 12 Tests so I think we've been performing okay."

Warne was speaking at the Australian launch of his book Shane Warne, My Illustrated Career and said McGrath "just needs a bit of bowling". "I think Glenn McGrath's had a fair bit of time out," he said. "I wouldn't be writing Glenn McGrath off, he's a champion and I think Australia need Glenn McGrath."

The selectors decided McGrath's best chance of reaching peak form during the Ashes was to bring him back through the Champions Trophy and last month's Malaysia tri-series. However, McGrath has been below his best in matches against West Indies and England over the past week. Andrew Strauss and Ian Bell struck 27 from his first four overs on Sunday before he improved in the latter stages to take 2 for 36.