Curtis Davies headed the visitors into first half lead and it was an evening that called for a bit of patience - patience that was rewarded when Robbie Keane bought the scores level on 67 minutes.
The real drama happened in the closing moments when West Brom keeper Tomasz Kusczak fluffed his clearance under pressure from the little striker and proceeded to drag him down in the penalty area.
Even though Mido stuck the ball in the back of the net, the whistle had already sounded and it was left to Robbie to hold his nerve and secure the points.
"It was unbelievable!" beamed Jermain down the tunnel afterwards. "Even at 1-0 down at half-time, the team spirit is so good that you go in and still really believe you can win the game. I certainly thought we could win it and I think all the lads did as well.
"We dug in and got what we deserved in the end. The fans were fantastic, a goal down at half-time they could have got frustrated but they got behind the boys and in the second half the atmosphere was brilliant. It was a great game.
It needed Jermain to keep a cool head in order to pounce when the ball spun into the area off Kusczak as the clocked ticked towards 90 minutes, although he admitted he was not aware of the exact location of the ball.
"The keeper took a bad touch, I felt sharp and was onto it straight away. It was good to get the penalty and the three points.
"I didn't actually know where the ball was when it was up in the air. When I saw it to get it under control he climbed over my back and I knew it was a penalty.
"Mido was a bit disappointed because he put it in and was celebrating, but I knew it was a penalty.
"West Brom are a difficult side to play against, they work hard and try to stop you playing. They have good players and I thought they caused a few problems up front - the lads at the back had to do well.
"We worked hard and, overall, I think we were the better side."
Jermain Defoe did not harbour any doubts over the team's ability to bounce back after going a goal down to West Brom on Monday night.