Bale ruled out of Milan trip
The flying Welshman, who scored a memorable hat-trick in the San Siro against Inter Milan in the group stage of the competition, has missed Tottenham's last four matches after suffering back spasms.
"Gareth is not too far away. He's not going to be fit, I don't think, for Tuesday but he's not too bad," Redknapp told reporters after Tottenham's 2-1 Premier League victory at Sunderland on Saturday.
"The specialists have seen it, he's had an epidural injection. Peter Crouch has had the same problem and he is fine - in fact, his back looked a lot worse on the scan."
Redknapp said Rafael van der Vaart should be fit for the last 16, first leg tie against the seven-times European champions despite him also missing the Sunderland victory.
The Dutchman came off at halftime during the win over Bolton Wanderers last weekend with a calf strain.
Between them, Bale and Van der Vaart have scored six goals in Tottenham's impressive first campaign in the Champions League. Midfielder Luka Modric is also a doubt for Tottenham after having his appendix removed last week.