The Saints playmaker made his comeback in the Boxing Day draw at Inverness after being sidelined since September with a shoulder injury. Lennon says the whole squad has been boosted by his return and the Buddies boss wants to see McGowan make an impact between now and the end of the campaign. He said:
"It has given everybody a lift just getting Paul back into training.
"We managed to get him back two games ahead of schedule and we will assess him today and see how he is.
"He will be a massive influence in this sprint now until the end of the season."
Another player who could be key for Saints is Steven Thompson, who has netted three goals in the last two games to bring his tally for the season so far to 10 goals. Lennon said: "Steven is very intelligent inside the box, he's a wonderful finisher, and he's on course to beat the record he had last season of 16 goals.
"He's in a good place just now, he's working extremely hard, he's looking fit, as fit as I've ever seen him.
"He is also contributing massively outside of his goals. "We have a lot of players hitting form at a very crucial period for us so long may that continue."
However, the Paisley club will be without Kenny McLean for a number of weeks after he underwent minor knee surgery today, although Lennon can take solace from a large part of the recuperation period taking place during the winter break. The manager said:
"Kenny went under the knife this morning, it was a minor operation for Kenny.
"He will get a little tidy-up and it's come at a good period for him as he's only going to miss two or three games.
"With the winter break coming, it gives him a great opportunity to hopefully get back for the game on the 19th.
"If not, he'll certainly be available for selection for the [League Cup] semi-final."
Saints travel to Tannadice to take on Dundee United in Sunday's Premier League clash, having picked up a win and a draw in their last two outings against Motherwell and Inverness respectively. Lennon said:
"Dundee United beat us narrowly 1-0 here the last time with a late penalty after us taking the game to them. It's important that we bring all our key strengths.
"Dundee United perhaps don't start the first half of the season particularly well but we know, over their history, that they finish extremely well on top.
"That's something we must be aware of. Hopefully we've got them in the right half of the year.
"We have had good results in our last two games - a win and a draw - against two teams who are sitting joint second top of the league.
"That's encouraging and will breed a little bit of confidence.
"But the main part of our success is the group of players working hard for each other and playing as a team.
"That's been the key to our joy at this moment in time."