Mulgrew is back in training after missing the Aberdeen game with a calf knock but James Forrest is a doubt again.
Celtic welcome their visitors hoping to get their season back on track after a surprise Scottish Cup defeat at the hands of Aberdeen - and Lennon believes that in doing so, they can launch a run that will see them end the season unbeaten.
"The incentive now is to go unbeaten the rest of the season. That's the target for them and to win the championship with a bit of style," he said.
"Some players are right at the top of their game. They have entertained all season, they have broken records and we want to finish the season in style rather than let it peter out. You can't let one bad game out of 26 deter what you are trying to do."
Tam Scobbie is back from suspension for St Johnstone's trip to Celtic Park but fellow defender Frazer Wright drops out with a ban.
Alan Mannus has returned to light training ahead of schedule after a broken thumb but is unlikely to be risked against the Scottish Premiership leaders.
Steven MacLean is also in light training following knee surgery but is not ready to play while Murray Davidson (knee) remains out.
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