Root criticised for continuing with injury-prone Wood late into Australia's second innings

England skipper Joe Root has drawn flak from former cricketers Steve Harmison and Mark Butcher for persisting with pace bowler Mark Wood late into Australia's second innings on Saturday, knowing that he is injury prone.

Wood bowled 15 overs, second only to spinner Jack Leach 21.5, in Australia's second innings on Day 4 of the forth Ashes Test at the SCG. While Wood took two important wickets, there are fears that he might get into another serious injury problem as the out-and-out England pacer has a history of breakdowns.

With Wood the only express pace bowler currently available with England in the absence of Jofra Archer and Olly Stone -- both absent with injuries - Root's decision to continue with Wood has been termed as "crazy".

The 31-year-old Wood has so far bowled 86.4 overs in three of the four Tests so far, with only 39-year-old Jimmy Anderson and Ollie Robinson bowling more for the tourists so far.

"He's (Wood) not exactly been less expensive than Jack Leach was, and the risk of damaging him before the final Test match at Hobart, bowling futile overs at the back-end of this innings is just madness to me," said Butcher on for BT Sport. "I think this is crazy, Mark Wood hurtling in here, I really do."

Wood has picked up eight wickets at an average of 37.62 so far and got the dangerous David Warner and Marnus Labuschagne in the second innings at Sydney, though Usman Khawaja smashed a century later in the day to give Australia an imposing total to defend.

The former cricketing stalwarts felt it was a futile exercise bowing Wood when Khawaja and Cameron Green were pressing on towards a declaration on Day 4.

"We've talked about Joe's captaincy and fielding positions and things that have been labelled at Joe, and I've stuck up for him a little bit," said Harmison.

"You talk about fielding positions for Leach, it's about how the bowler bowls. But some decisions are baffling, and to have your strike bowler bowling overs when they're setting up a declaration, when they've got a bit of an injury track record and background anyway, I just think it's madness. We can't go to Hobart and compete unless we've got Mark Wood in the side," added Harmison.

"You don't want him to get an injury. That would arguably cap the tour off if you lost your premier fast bowler before the end of this Test match going into Hobart, bearing in mind we've broken Ben Stokes for not having the preparation, the miles in his legs."