Flower's sixth Test century carried Zimbabwe, needing 258 to avoid an innings defeat, to 235 for 6 before bad light ended play nine overs ahead of time.
The Zimbabwe skipper, who was top scorer in the first innings with 74, has now scored more Test centuries for his country than any other player, passing his brother Grant's five tons. Flower has batted for 315 minutes, faced 229 balls and hit just seven fours - an indication of how hard he worked as well as the slowness of the outfield.
Zimbabwe, 34 for 3 overnight, batted watchfully in the first session in which they lost only one wicket when Neil Johnson (14) drove uppishly at Nuwan Zoysa to be caught in the gully by Marvan Atapattu.
The next wicket fell just before tea when Murray Goodwin was run out for 48 in bizarre fashion to end a fifth-wicket stand of 101 with Flower. Goodwin blocked a delivery from Chaminda Vaas, who kicked the ball towards the slips. From there, Tuwan Dilshan threw down the stumps with Goodwin having strayed out of his ground in his own failed attempt to kick the ball.
Alistair Campbell (5) was then leg before to Muttiah Muralitharan's off-spin, and Sri Lanka were closing in on victory. However, Flower and Andy Whittall (27no), batted solidly in their sixth-wicket stand of 76. However, with few wickets in hand and Muralitharan extracting sharp turn, Sri Lanka should wrap up victory today.
Sri Lanka won toss; Third day
Zimbabwe - First innings 174 (A Flower 74).
Sri Lanka - First innings 432 (T Dilshan 163no, D P M Jayawardena 91).
Zimbabwe - Second innings
(Overnight: 34 for 3)
M W Goodwin run out (Dilshan) 48
N Johnson c Atapattu b Zoysa 14
*A Flower not out 107
A D R Campbell lbw b Muralatharan 5
G J Whittall not out 27
Extras (b1 lb11 nb5) 17
Total (for 6) 235
Fall: 1-5 2-28 3-28 4-51 5-152 6-159.
To bat: G Brent, B Strang, H Olonga, E Matambanadzo.
Bowling: Vaas 29-5-67-1 (nb-1), Zoysa 11-2-24-1, Wickramasinghe 22-8- 39-0 (nb-1), Muralitharan 32-9-59-2 (nb-3), Jayasuria 6-0-31-0, Arnold 1-0-3-0.
Umpires: R B Tiffin and S A Bucknor (WI).Reuse content