The visitors had long periods of pressure from the 20th minute onwards – and had much the best of the second half – but were undone in two key areas; their lineout was poached and misfired frequently under the pressure of the skyscraping Richie Gray and, for all their field position and pressure, they lacked the invention or penetration to breakdown a resolute home defence.
The Warriors had led from the first, but the game was in the melting pot as late as the 64th minute when No 8 Francke Horn scored the Emirates Lions’ second try.
The home side eased their growing alarm with a penalty from scrumhalf George Horne – who landed five from five on the night – and a fourth try, from replacement wing Tom Jordan, with five minutes remaining made the game all but safe in what was a rare Glasgow entry to the visitors’ 22.
Replacement hooker Morne Brandon scored the Emirates Lions’ third a minute later – with flyhalf Gianni Lombard adding a second conversion – and the team from Johannesburg were pressing all the way to the final whistle in an ultimately forlorn effort to reach the last four.
After crushing the Dragons 73-33 in the round of 16 a week ago, the Warriors found their fellow Vodacom United Rugby Championship side Lions a far harder nut to crack, despite building a 14-0 cushion midway through the first half.
On both occasions their tries came from attacking lineouts in the Emirates Lions’ 22. No 8 Jack Dempsey, running in the inside centre channel, burst through from 10 metres after a maul had been faked to confuse the defence and then left wing, Jamie Dobie, finished in the corner after the initial close-range drives had been held.
Horne converted both but the visitors were far from throwing in the towel and only resolute home defence prevented them closing the gap by half time. They had four lineouts in the left-hand corner and then a centerfield scrum under the poles in the final 10 minutes of the half – only to be repelled each time.
Scrumhalf Sanele Nohamba did ground the ball on the line just before the break – after spotting a gap a few metres out – but was denied the try for a double movement.
But he got a deserved breakthrough for the Emirates Lions, three minutes after the restart. The visitors resumed as they had left out – on the attack – and when they were awarded a penalty 10 metres out, Nohamba reacted more quickly than anyone to tap to himself and twinkle toe through the retreating defence to score a try he converted himself.
Prop Zander Fagerson bullied his way over from less than a metre to restore the 14-point margin but from there on in it was an arm wrestle with Glasgow’s defence ultimately proving itself resilient enough to repulse the Lions’ one-off runners.
Glasgow Warriors 31 (14) – Tries: Jack Dempsey, Jamie Dobie, Zander Fagerson, Tom Jordan. Conversions: George Horne (4). Penalty goal: Horne.
Emirates Lions 21 (0) - Tries: Sanele Nohamba, Francke Horn, Morne Brandon. Conversions: Nohamba, Gianni Lombard (2).