Poor discipline and defence have again proven costly for the NSW Waratahs, whose Super Rugby finals hopes have taken another hit with a 44-28 loss to the Highlanders in Dunedin.

The Tahs’ hopes of topping the Australian conference dropped on Saturday when they surrendered a 14-13 halftime lead and conceded 17-straight points after the break.

The Highlanders scored six tries to four.

They capitalised on a one-man advantage early in the second half, when they scored two tries while Waratahs lock Dean Mumm was in the sin-bin.

Mumm, who earlier this week announced he would retire at the end of this year, was given a yellow card for a dangerous tackle, but looked a little unlucky.

A converted try to replacement halfback Jake Gordon cut the deficit to nine points and lifted the Tahs in their push for a bonus point.

Those were quickly extinguished with Daniel Lienert-Brown and Lima Sopoaga touching down for the home team, before Gordon scampered away after taking a quick tap to notch his second five-pointer.

The loss leaves the Tahs second in the Australian conference behind the Brumbies, who can stretch that lead by beating the Jaguares on Sunday morning in Buenos Aires.

Down 10-0 after 17 minutes, the Waratahs produced some sparkling passages of play to hit the front by the break.

Fullback Israel Folau crossed after beating flanker Elliot Dixon with some quality footwork.

Winger Taqele Naiyaravoro pounced on a superb cut-out pass from halfback Nick Phipps to crash his way over for a try just before the break, with the conversion to five-eighth Bernard Foley giving the Tahs the halftime lead.

The Highlanders quickly regained the lead through hooker Liam Coltman after a forward drive from the penalty awarded after Mumm was binned.

Winger Tevita Li won the chase to a delightful chip from centre Malakai Fekitoa to expand the Highlanders’ lead before Mumm returned.

Rob Thompson added a try after the Waratahs were back to 15 men, as the Highlanders sprinted to a 30-13 advantage.