The hosts have already reclaimed the urn with three big victories in the opening tests against a woeful England side that suffered a further blow on Sunday with the shock retirement of spearhead spinner Graeme Swann. (Agencies)
Australia opener Chris Rogers has hit two fifties in his six Ashes innings but said on Saturday he still felt on shaky ground. Lehman said the 36-year-old would keep his place in what he hoped would be an unchanged side for the Melbourne test.
"Our top order know they have to make some more runs and one of the big things is making them in the first innings," Lehmann told reporters on Sunday.
"We need our guys performing straight up, day one, if we bat first."
Rogers opening partner David Warner has been a great form with the bat, smashing centuries in Perth and Brisbane and an unbeaten 83 in Adelaide.
But Lehmann, who said there was 'no dramas' with Rogers, opted to share the praise, hailing the work of the duo whose performances have been a huge improvement on the 3-0 away series loss to England earlier in the year.
"They have had some good opening partnerships for us, which we didn't get in England," the former batsman said.
"The 150 they put on in Perth, when we had a lead but we needed to start well... he's (Rogers) contributed."
Some of those runs came off the bowling of Swann, who had struggled to replicate his Ashes successes of past in the opening three matches of the current series before announcing his shock retirement.
His departure follows that of number three batsman Jonathan Trott, who returned home after the first test defeat with a stress-related illness.
Lehmann did not want his side to become distracted by the crisis in the England camp.
"To have two senior guys not play, that's maybe an advantage, but also younger guys get a chance," Lehmann said.
"I only worry about us. That's how we deal with it and that's all we can do.
"I'm sure they weren't worried about us last time either," he added, in reference to the 3-0 Ashes defeat in England.
The hosts have already reclaimed the urn with three big victories in the opening tests against a woeful England side that suffered a further blow on Sunday with the shock retirement of spearhead spinner Graeme Swann.