The Seagulls looked as though they would be left frustrated after Neal Maupay missed a first half penalty and spurred other chances when Diogo Jota’s strike put Liverpool ahead on the hour.
Jurgen Klopp’s side had two goals disallowed for offside by VAR but looked to be holding on for victory when the technology intervened again moments into added time.
Danny Welbeck was fouled in the box and referee Stuart Attwell changed his mind after he checked the pitch-side monitor. And Gross kept his cool, drilling the penalty low into the bottom corner to secure the hosts an unlikely point.
However, on the balance of play it was no more than Graham Potter’s side deserved for their part in an entertaining Premier League contest.
Both Roberto Firmino and then Mo Salah got in behind Brighton early on, but neither could hit the target and it was Albion who created the first clear opportunity after 10 minutes.
Maupay’s neat ball through put Aaron Connolly through on goal down the middle, but he couldn’t hit the target with only Allison to beat.
Nine minutes later Albion squandered an even better chance. Connolly continued to cause Liverpool problems, and after latching onto Yves Bissouma’s pass was bundled over by Neco Williams inside the area.
However, despite sending Allison the wrong way Maupay saw his penalty go wide of the right hand post.
Maupay then hobbled off five minutes after his miss with what looked like a tight hamstring, and his replacement Leandro Trossard had a sight of goal shortly afterwards but again failed to test Allison.
And Liverpool nearly made these misses pay after 35 minutes. Firmino helped on Allison’s long ball forward and Salah was away, and fired past Mat Ryan. However, he had strayed an inch or two in front of Ben White and the goal was ruled out for offside by VAR.
Danny Welbeck then tested the Liverpool keeper early in the second half. After driving forwards and getting past Firmino, the striker saw his low strike turned away by Allison.
Albion had been very much in the game with an hour played, but Liverpool punished their first defensive lapse to take the lead. Salah teed up Jota, who got past Adam Webster and Trossard before firing beyond Ryan and into the bottom corner.
Liverpool looked in control now, without really threatening to score again, whilst Albion were also struggling to create a chance from open play. Solly March got a 25-yard free-kick on target, but Allison made a comfortable save.
The Seagulls looked to up the ante in the closing stages, although they had another VAR reprieve when Sadio Mane headed in Jordan Henderson’s free kick but had strayed offside.
Liverpool looked as though they had the job done, but when the tireless Welbeck was fouled by Andy Robertson as the Reds defender looked to clear, Gross kept his cool to earn Brighton a point.