Malakai Fekitoa scored a fine solo try late in the game to hand the Highlanders a 17-10 victory over South Africa's ailing Bulls in wet and muddy conditions at Loftus Versfeld.
Both sides finished with 14 players in conditions that stifled running rugby as the Highlanders extended their winning run to seven matches, while the Bulls' play-off hopes now look ever more remote.
Fullback Matt Faddes scored the opening try for the visitors, who had to play the final 16 minutes a man down after a red card for wing Waisake Naholo for a reckless tackle with the game evenly poised at 10-10.
The Bulls scored their try through fullback Warrick Gelant, but just as they threatened to seize the initiative, lock RG Snyman also saw red for a shoulder charge in a passage of play that appeared to have ended in a home try before the referee pulled the play back and it was disallowed.
It would prove a pivitol moment in the game as the Highlanders grabbed the winning points four minutes later.
The conditions meant the match was reduced to a tussle between the forwards and it was the Bulls who looked to have the ascendency when Naholo was sent-off.
The wing led with his shoulder into the face of home centre Burger Odendaal and the television match official confirmed a red card.
The Bulls took a grip on the game and camped near the Highlanders line, with prop Pierre Schoeman going over under the posts.
However, Snyman quite clearly cleaned out at a ruck with his shoulder in the build-up and what looked a winning try was rightfully chalked off.
He was made to pay further for his moment of madness when Fekitoa found a gap in the Bulls defensive line and skipped past three players to score.