The hosts could wrap up the series 3-0 with victory at the WACA but with temperatures soaring in the Western Australian capital, Lehmann said James Faulkner looked likely to remain 12th man for a third straight Test.
"We'll have to look at the wicket first and foremost, see what it's like," Lehmann told the Cricket Australia website.
"If we think it warrants (Faulkner) playing and the four quicks so be it.
"But, look, it's going to be hot weather here - it's 35 (degrees Celsius) and getting up to 40 on Monday - so ... I think we'll play the spinner.
"Again, we've got to work out who has pulled up fit from the last Test match, so ... we'll see what happens."
Lyon's inclusion in the Perth Test which starts on Friday would mean Australia fielding an unchanged side for the third time in the series, which they opened with impressive victories in Brisbane and Adelaide.
After just a three-day turnaround following the 218-run victory in Adelaide, though, Lehmann would be wary of putting too much of a workload on his pace battery of Mitchell Johnson, Ryan Harris and Peter Siddle in the searing Perth heat.
Lyon has the ability to hold down an end to give the seamers a break and showed in the 381-run victory in the series opener in Brisbane that he can take key wickets on a bouncy wicket.
That is exactly what the WACA's head groundsman Matt Page said Lyon should expect.
"Spinning-wise you'll get the footmarks day four, day five," he told reporters in Perth on Wednesday. "You'll get a bit of turn out of there. Spinners here normally get the bounce more than anything."
Australia can also look to Steve Smith's leg spin for overs and Lehmann said after the Adelaide Test that they would be looking for a bigger contribution from Shane Watson.
"He's been under-bowled," the coach said. "He could have bowled more in the first Test, and this Test match.
"From our point of view that's handy. But he's an all-rounder, so we expect him to bowl more. And he'll certainly have to in Perth if the weather is hot."
Johnson will be eager to see as much of the ball as possible after taking 17 wickets in the first two encounters with the English, who arrived in Australia looking to win a fourth successive Ashes series.
"When a bowler is bowling at 150 (kph) it's not easy," said former Test batsman Lehmann. "When I was playing, 150ks would get me out every time. Simple fact of life, it's tough work.
"He's been impressive. He's confident. Our challenge is to keep him going and bowling that way. It's exciting for Test match cricket."