Pulis felt the Baggies were second best to every ball against Aston Villa before half-time during their Premier League loss and insists the second half was a different game.
As such, the Welshman admits his side's poor first was the key reason behind their 2-1 defeat at Aston Villa's hands.
“Villa were better than us in the first half,” the West Brom boss told reporters. “They were quicker, kept the ball better and we wanted half-time. The second half was a different game."
West Brom goalkeeper Ben Foster, meanwhile, erred at a crucial moment against Villa and came under fire for ultimately costing his side points during the local derby on Tuesday night.
But his manager has defended him after he mistake, saying Foster has been 'fantastic' this season and that no one at the Hawthorns will be criticising the 31-year-old.
Pulis added: “He has been fantastic for us all season, he has won us games and he has had an off night but there'll be no one here who will criticise him.
"I don't have to speak him, he knows. We'll dust ourselves off and get going on Thursday."
Aston Villa's win lifts them up to 17th in the Premier League table, outside the relegation zone and just five points behind 13th-placed West Brom.
A better first half from the Baggies, however, and Pulis will argue his side could have ensured a much different result. It's a good thing he'll have a second crack of the whip this weekend, then, when West Brom travel to Aston Villa once again in the FA Cup quarter-finals.