The former Birmingham City player returned to the Midlands to pounce on an 84th minute cross from the left hand side by Patrick Van Aanholt after a defence-splitting pass by substitute Jordi Gomez.
The equaliser was a reward for the Black Cats who saw a fifth minute lead slip away thanks to a controversial penalty decision by referee Neil Swarbrick who pointed to the spot after Baggies frontman Victor Anichebe went down easily in the 42nd minute.
The Mackems started the game the strongest and took the lead after the West Brom defence was caught napping. A free kick 35 yards out on the right hand side was whipped in by Larsson and former Manchester United player Wes Brown drifted, unmarked to the far post where he headed back into the area. The ball was cleared to the edge of the box where Lee Cattermole rifled a fierce shot into the top right hand corner of Ben Foster's goal.
The Baggies' response was slow and sluggish and certainly wasn’t what new boss Irvine would have wanted on his first match in charge in the top division. Despite some good possession in the middle of the park, the home team could only manage a couple of long range efforts which Vito Mannone in the visitors’ goal dealt with comfortably.
But with three minutes to go until half time, Craig Gardner skipped around the edge of the area and fed a ball to the right of Anichebe. The big Nigerian striker spun off his marker Valentin Roberge and went down lightly under pressure from the Sunderland defender. The referee surprised most of the fans packed into The Hawthorns by pointing to the spot and England under-21 striker Saido Berahino converted coolly to level the game.
Both teams started the second half brightly and West Brom were unlucky not to go ahead. A free kick was punched into the air by under pressure Sunderland keeper Mannone and as he tried to get back onto his feet he was adjudged to have been obstructed by Baggies captain Jonas Olsson as Baggies defender Craig Dawson headed the ball inches over the line. The Goal Decision System later showed it was a goal but referee Swarbrick reacted to a flag by his assistant and ruled it out.
The closely competitive game continued to hang in the balance until the 74th minute when West Brom finally went ahead. Olsson burst forward out of defence and played a ball into the feet of Graham Dorrans who turned in from the left hand side onto his favoured right foot and unleashed a venomous shot which Mannone could only parry straight into the path of his former team mate Gardner on the left. He lofted a left-foot cross to the far post where an unmarked Berahino tapped in his second of the match from two yards out to set up a thrilling finale.
Under Pepe Mel last season West Brom were guilty of squandering the lead on a number of occasions and again their demons came back to haunt them. With 84 minutes on the clock substitute Gomez slipped the ball through the Albion defence on the left where overlapping full-back Aanholt whipped in a cross which Larsson hit home from five yards to ensure that both teams left The Hawthorns with a point.
After the game Black Cats boss Gus Poyet questioned the referee’s decision to award the first half penalty but said he did not want to say too much ‘to avoid getting into trouble’.
“I don’t want to start the season talking about referees. I want to talk about football and I thought we played well in patches.”
Baggies boss Alan Irvine said he had enjoyed his debut as a Premiership manager and was quick to admit ‘it was a soft penalty’.
“I'm disappointed really that we didn't win because I felt there were a lot of good things. We controlled the first half and you didn't want half-time to come. We didn't play as well in the second-half.”
Irvine was full of praise for two-goal striker Saido Berahino who he predicted ‘could have a very big season’.