The Baggies have suffered two consecutive defeats at the hands of Manchester City and Newcastle United respectively, but Dorrans believes that the way they played in each of those matches should inspire the players to pick up all three points.
"There are no easy games in this league but we'll be going into the game on Monday looking to get three points," said the Scotland international.
"We've had two disappointing results but we've played really well in both games and hopefully, even if we don't play as well on Monday, we get the three points, as that's all that matters. But they've got good players. I remember playing them in pre-season before the start of last season and they were a good team.
"It will be tough because they'll be coming here thinking they should be getting points. They've been to some tough grounds - Arsenal, Everton and West Ham are hard places to go. I'm sure they'll be looking to come here and get their first away win. But we'll go into it confident because of our previous two games."
West Brom currently sit eighth in the Premier League table, while Southampton are languishing down in 19th place.