The Celtic captain is OUT of Sunday's SPL game against Hearts at Parkhead after taking anti-inflammatories and a pain-killing injection to get through the Champions League victory over Spartak Moscow this week.
Brown's ongoing hip complaint means he will not cope with two games in a week and Levein will have to pick either the game against Wales next Friday night or Belgium the following Tuesday.
"He didn't train for us on Monday and then did two strides on the pitch on the warm-up on Tuesday and walked off," said Lennon. "With all the press there, we told him to stay on and let on he was okay.
"He took about 14 anti-inflammatories and took an injection in his backside and played a real captain's role, a brilliant performance.
"He is one of those players for whom my admiration grows every day. Craig knows the situation.
"He will go with Scotland and he will play, but I don't know that he would be able to play the two games."
Adam Matthews is 50-50 for the tie against Hearts, but Joe Ledley and Beram Kayal are both back in contention.
Meanwhile, the Celtic manager declared Gary Hooper's performance in Russia this week as the BEST display he has seen from a Hoops striker in an away game in Europe – and that included the legendary Parkhead forward line of Henrik Larsson, Chris Sutton and John Hartson.
Hooper has been overlooked for international recognition, but Lennon believes that if he maintains his current form it will be impossible for him to be overlooked.
"He can't do any more," said the Celtic boss. "His performance is one of the best I have seen from a striker for Celtic away in Europe and I include Henrik and Chris and all the other top players that we have had."