The Lions will travel to Christchurch to play in their third consecutive final and stare down a rematch with the Crusaders, the team that beat them in their own backyard to claim the title last year, after beating the Waratahs 44-26.

They richly deserve the opportunity, outscoring their Australian opponents six tries to four under a deafening stadium soundtrack of Afrikaans pop songs, big cat sounds and the Shosholoza, an African miners' song that rung out at the same venue when Francois Pienaar's Springboks won the World Cup final in 1995.

They produced the more complete performance, overcoming a 14-nil deficit after 10 minutes by sending in turnover merchants Malcolm Marx and Kwagga Smith to disrupt the Waratahs' attack, using their maul to score two tries and injecting the likes of sizzling young talent Aphiwe Dyantyi to slice and dice the visitors' defences.

The Waratahs burst out of the blocks with two converted tries to Ned Hanigan and Israel Folau, and they didn't ever stop believing a win was possible, even when Damien Fitzpatrick was sent to the bin for running offside and the Lions racked up an 18-point lead with 10 minutes to go. Jake Gordon scored to keep them in the match but a Courtnal Skosan try put the result beyond doubt.

The Lions didn't get on the board until the 21st minute but they made up for lost time. Smith gave Sekope Kepu the slip to score and five-eighth Elton Jantjies converted to make it 14-7.

Hooker Marx almost repeated his quarter-final intercept try exploits but Kurtley Beale did well to pull him down just outside the Waratahs' 22.

But 24-year-old winger Aphiwe Dyantyi made the play of the match, recapturing his own chip kick and sprinting from outside halfway - past Curtis Rona and Foley - to score in the 26th minute. Jantjies missed the conversion to leave his side trailing 14-12.

The Television Match Official disallowed Franco Mostert's try with seven minutes left in the half, ruling that the ball was knocked forward to second rower Marvin Orie and then back to Mostert.

They righted things two minutes later with a Lions' Special driving maul try. Jantjies slotted the conversion from the sideline to put the Lions ahead 19-14.

The hotel corridor walk-throughs with forwards coach Simon Cron paid off when NSW loosehead Tom Robertson took a Tolu Latu short throw in front of the lineout and bolted over to score with less than a minute on the clock. Foley missed the conversion and the chance to go into the sheds with his team in the lead. The scores were locked up 19-all.

With the scores reset to zero the Waratahs went on the attack, spreading it side-to-side in search of some space, but over-cooking a few of their passes to relieve pressure on their opposition.

Lions snafflers Marx and Kwagga Smith made pests of themselves, forcing two turnovers inside their 22.

Fitzpatrick's send-off hurt, the Lions going for the jugular with a driving maul at the visitors' line and Marx bagged his second in the 59th minute. Jantjies conversion timed out, leaving the Lions 27-19 up, but Smith scored in the 63rd to make it 35-17 with 15 minutes left.

A Jantjies penalty made it 37-19 and while Gordon's try in the 76th minute gave some consolation, the Lions weren't finished, sending Skosan over with a cross kick to seal up the semi-final 44-26.

The Waratahs will fly home knowing they gave it everything, but were hurt by their final-round loss to the Brumbies, which robbed them of a home semi-final.