Replacement hooker Sam Riley scored the winning try as Harlequins recorded their first-ever knockout Investec Champions Cup victory.
The Quins had looked in control at half-time leading by 14 points thanks largely to fly-half Marcus Smith who scored a try and three conversions, with inside centre Andre Esterhuizen and left winger Cadan Murley also crossing.
Glasgow, who had led early through second row Scott Cummings came storming back with hooker Johnny Matthews scoring their second try.
When Warriors scrum-half George Horne ran over a third try to level the match momentum seemed to be shifting.
Horne then slotted a penalty to complete the second half fightback and gave his side a three-point lead.
However, buoyed on by defending 10 minutes with 14 men after replacement loose-head prop Joe Marler saw yellow, once the hosts were restored to a full compliment they rallied.
Riley was on hand to drive over the winning try to book his side’s quarter-final place where they meet either Saracens at home or a trip to Union Bordeaux-Begles, who face each other on Saturday evening.
Talking Point – Harlequins make history with dramatic fightback
Harlequins looked like heading out of this year’s Investec Champions Cup after seeing their 14-point half-time lead overturned.
However, after keeping Glasgow at arm’s length home advantage was key in the final 10 minutes.
The Twickenham Scoop believed a late victory was on the cards and urged their side forward with Sam Riley scoring the winning points.
The Quins will have lots to reflect on from that second half performance when Glasgow could have won the tie.
Player of the Match – Marcus Smith (Harlequins)
The first-half performance by Marcus Smith put Harlequins into a commanding lead with a standout display.
The fly-half provided a chipped assist for the opening try before jinking around the Glasgow defence to score the second himself.
Smith also played his part with a key pass for Harlequins third try and was faultless with his kicking all evening.
Player Ratings
Harlequins: Green 7, Lynagh 6, Beard 6, Esterhuizen 7, Murley 8, Smith 8, Care 7, Baxter 6, Walker 7, Collier 7, Herbst 7, Hammond 7, Lewies 6, Evans 7, Dombrandt 7
Replacements: Riley 7, Marler 6, Lewis 6, Launchbury 7, Trenholm 6, Lawday 6
Glasgow Warriors: McKay 7, Steyn 7, McDowall 7, Tuipulotu 7, Rowe 6, Jordan 6, Horne 7, McBeth 7, Matthews 6, Z Fagerson 6, Williamson 6, Cummings 6, M Fagerson 6, Darge 6, Dempsey 6
Replacement: Hiddleston 6, Kebble 6, Sordoni 6, Manjezi 7, Venter 6, Dobie 6, Weir 7
Match Highlights
TRY! HARLEQUINS 0 GLASGOW WARRIORS 7 (CUMMINGS)
2 – Glasgow finish a try involving phase after phase of pressure before Cummings grabs the ball out of a ruck to ground the ball. Horne is perfect with the kick.
12 – Harlequins think they have scored a try in response but as Murley is about the ground the ball he loses control as McDowall makes a last ditch challenge. TMO make a call and the try is ruled out
TRY! HARLEQUINS 7 (ESTERHUIZEN) GLASGOW WARRIORS 7
22 – Smith chips over the top of the Glasgow defence for Esterhuizen who scampers through on the wing and grounds the ball. Smith then kicks Quins level with the conversion from the touch-line.
TRY! HARLEQUINS 14 (SMITH) GLASGOW WARRIORS 7
33 – The ball is picked out the scrum for Smith who jinks two players and crosses the whitewash under the posts. The Quins’ kicker then kicks the conversion under the posts.
TRY! HARLEQUINS 21 (MURLEY) GLASGOW WARRIORS 7
41 – With the clock in the red Quins kick to touch deep in the Glasgow 22. Smith plays a perfect pass for Murley to score out wide. Smith finishes an impressive half by kicking the resulting conversion.
TRY! HARLEQUINS 21 GLASGOW WARRIORS 21 (HORNE)
49 – Glasgow have completed a fightback with two tries in as many minutes. Some quick releases under pressure resulted in Horne finding space to run over.
Horne converts his own try to put his side level.
TRY! HARLEQUINS 21 GLASGOW WARRIORS 14 (MATTHEWS)
52 – Rolling off the back of a driving maul Darge and McDowall drive forwards dragging Matthews with him creating space to dot down. Horne kicks the conversion and Glasgow are back to seven points.
TRY! HARLEQUINS 28 (RILEY) GLASGOW WARRIORS 21
75- Glasgow try and collapse a driving maul but the Quins forwards are too strong and Riley is on hand to cross the whitewash in his first ever Champions Cup try. Smith as expected kicks to give his side a four-point lead
Key Stat
Harlequins ended a run of six straight defeats in knockout Champions Cup games, including last 16 exits in both of the last two years.
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