Centre Malakai Fekitoa scored a fine solo try late in the game to hand the Otago Highlanders a 17-10 victory over South Africa's ailing Bulls in wet and muddy conditions at Loftus Versfeld in Pretoria on Saturday.

Both sides finished with 14 players as the Highlanders extended their winning run to seven matches, providing another blow to the Bulls dimming play-off hopes.

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 had ended in a home try before the referee pulled the play back and it was disallowed.

It would prove a pivotal moment in the game as the Highlanders grabbed the winning points four minutes.

After the Bulls had taken an early lead via a penalty from flyhalf Tiaan Schoeman, the Highlanders grabbed the opening try as Faddes beat three home defenders to collect a chip ahead and race clear for a score under the posts.

The lead was extended shortly afterwards when replacement flyhalf Fletcher Smith slotted a penalty to give the Highlanders a 10-3 halftime advantage.

The Bulls fought back early in the second half though as Gelant profitted from a mistake by Faddes and crossed for a converted try to level the score.

The conditions meant the match was reduced to a tussle between the forwards and it was the Bulls who looked to have the ascendancy when Naholo was sent-off.

The wing led with his shoulder into the face of home centre Burger Odendaal and the Television Match Official (TMO) 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, the 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.