Ambrose is expected to feature for Nigeria against Burkina Faso on Sunday in the Africa Cup of Nations final - two days before the Hoops host Juventus in the first leg of their last-16 clash.
"Nigeria did fantastically well and Efe has played brilliantly in the game so I'm delighted for him in one way, but obviously very frustrated in another," Lennon told CelticTV.
"The final is on Sunday and he probably won't get back until Monday evening, so he would be a doubt.
"We will get him into the squad and see how he is feeling."
Celtic are in Scottish Premier League action on Saturday when they make the trip to Inverness Caledonian Thistle.