By Marcus Chhan
Manassero shot a seven under par 64 to go 11 under while South Africa's Louis Oosthuizen is close behind following a 65 to post nine under at the end of the third round which was completed on Sunday morning because of rain delays on Thursday and Friday.
The overnight leader was Denmark's Thomas Bjorn who held a one shot lead over England's Chris Wood after managing three holes of his third round on Saturday evening. When play resumed on Sunday morning at 7.30am local time, the Dane completed the front nine in one under but a damaging back nine which included four bogeys saw him drop back from the lead.
Bjorn finished with a three over par 74 to leave him five shots off Manassero at the top of the Barclays Singapore Open leaderboard going into the fourth round.
Englishman Wood remains in better shape as his one under par 70 means he is only three shots back from Manassero.
It could have been so much better for the Italian, though, had he not missed a make-able birdie chances on 15 and 16. However, the 19-year-old starlet made up for it with a pin-point approach shot on 18 to set himself up for an easy birdie putt to go 11 under.
Oosthuizen had earlier also birdied the 18th to remain very much in the hunt at the Serapong course in Sentosa.
The first groups who had finished their third round on Sunday are already out on the course for the final round as organisers try to avoid going into an extra day.
Tournament director Jose Maria Zamora has confirmed that in the event Sunday's fourth round is not completed, it will be a Monday finish.