Saints were back to their best as goals from Shane Long and Dušan Tadić sealed a 2-0 victory against Watford and ensured they returned to winning ways.
The Baggies visit St Mary’s on Saturday and Koeman is hoping he midweek performance will lead to a positive display against Tony Pulis’s side.
“I hope a lot,” said Koeman when asked what Wednesday’s win would have done for the team’s confidence. “At least it was an important win.
“That always is good for the confidence of the players, but we know it’s a difficult one against West Brom.
“We didn’t score any goals in the last three matches against West Brom and it’s difficult, but we play at home and we keep going.
“If we keep the level we showed on Wednesday, then I’m very positive.
“It was an important win out of the situation of the team and okay, that gives everybody a lot of confidence and we like to show it again on Saturday.”
Koeman stated at the start of the week how important the two home fixtures against Watford and West Brom, and the Saints boss is hopeful of making it two from two on Saturday.
“Normally we game by game and the next is always the most important, but after a bad run of results we had two home games and of course, then you need points,” Koeman told youtube.com/southamptonfc
“You need the wins. The first we did that against Watford and we try to win the second one now.
“The win against Watford gave the players a good boost.”