The 21-year-old – a reported target for Rotherham and Sheffield Wednesday – missed last week’s 2-1 home defeat by Spartak Trnava with a thigh injury, but is in the squad for Thursday’s match, which kicks off at 6.30pm BST.
Defender Steven Anderson and midfielder Chris Millar are both expected to feature after proving their fitness this week.
St Johnstone manager Tommy Wright insists all is not lost as his side look to recover from their lacklustre first-leg display.
He said: “We are quietly confident. There’s been a lot of disappointment in the squad and hopefully we can channel that with a better performance. When players come out and criticise themselves, it shows they are hurting.
“I think there is a determination to try and rectify things and if we put in a better performance, I genuinely believe we can turn the tie around.
“We need to score two goals and ideally you want to be solid. We have to cause them more problems. We did that in the last 10 minutes of the first leg and they didn’t really handle it well.
“This squad has a habit of defying the odds and turning things round when people don’t expect it.
“Stevie May will play. I’ve been kept up to date with what’s going on but I said to the chairman if any deal is done we need to make sure we have him available for Thursday.”