Singh birdied two of the last four holes at Valderrama to dissolve a logjam at the top of the leaderboard, ending three rounds at 3-under-par 210 for a one-shot lead over four players.
Already a four-time winner on the Asian Tour, Singh finally broke through for his first European Tour win at the Volvo China Open six months ago. Along the way, he learned something about closing out a victory.
'I've got to just keep my head down and go,' said Singh, who was the first Indian golfer to qualify for The European Tour when he won his tour card in 1997.
That might be a better idea than looking back, where there are 11 players within three shots of Singh's lead.
Spain's own Sergio Garcia, the world No. 9, shot his second consecutive 1-under 70 and shares second place with Swedes Johan Edfors (69) and Henrik Stenson (73) and Englishman Lee Westwood (72) at 2-under 211.
John Bickerton (70) and David Lynn (72) of England are one shot further back at 212.
Among the remaining pack, there are four players vying for their first Order of Merit title as the European Tour's leading money winner.
Current leader Paul Casey of England had his best round of the week, an even- par 71 that moved him into a tie for 32nd place at 6-over 219. Casey continues to recover from a virus that required him to receive an injection on Thursday, when he opened with a 76.
Each of his challengers for the Harry Vardon Trophy sits in considerably better position, due mostly to that first-round score.
'Unfortunately the tournament is lost,' Casey admitted. 'There's nothing I can do about that. The first two days when I was ill pretty much killed off my chances of being in contention.
'Whatever happens happens,' he added. 'It would certainly be disappointing (not to win the Order of Merit) but I don't think it would be a crushing disappointment. If it does not happen, I have plenty more chances. But I certainly want the Order of Merit before I hang up the clubs.'
Irishman Padraig Harrington, who snared second place in the rankings with a victory two weeks ago, had a 72 on Saturday but remains within striking distance at 1-over 214.
Harrington was 2 under through 11 holes, but bogeyed three straight from No. 14 to fall into a tie for 13th place.
'Four behind is not the end of the world, but I've put a lot of people between me and the lead and you've got to think somebody is going to shoot a decent score (Sunday),' said Harrington.
'It's not insurmountable, but when I was coasting along winning was a lot easier prospect than it is now.'
The No. 3 and 4 challengers, Englishman David Howell and Swede Robert Karlsson, are tied for eighth place at even-par 213 after both shot 1-under 70.
Howell, once vying to become the first wire-to-wire Order of Merit champion before he suffered a shoulder injury, birdied five consecutive holes early in his round. But he posted four bogeys without another birdie the rest of the way.
'I was in a nice little zone early on,' Howell said, 'but then came the three- putt. Classic error, momentum lost. After being five under through seven it was obviously disappointing only to score 70.'
Karlsson recovered from a 74 on Friday and birdied the 17th hole to get to even par. He and Howell share eighth place with Sweden's Niclas Fasth (71), France's Raphael Jacquelin (69) and Germany's Marcel Siem (72).