Saints were well-and-truly second-best at the Hawthorns last November, ending up on the wrong end of a two-nil scoreline.
That result left us rooted to the foot of the Barclays Premier League table, while the Baggies were flying high in fifth.
Schneiderlin was part of the team beaten that evening, and the Frenchman says he's intent on showing tomorrow's opponents just how much he and his teammates have improved since then.
"They beat us two-nil earlier in the season, and there was no dispute – they played a lot better than us that night," Morgan says in tomorrow's official matchday programme.
"We had a nightmare, and I had a nightmare myself. It was a very low point.
"Everyone was very down at the end of the game – at that point of the season we had lost our spirit. It was very hard to take that night, but we’ve bounced back.
"We owe them one [tomorrow] because we want to show them that we’ve come a long way. We’ve worked very hard to be at the level we’re at now.
"We want to beat West Brom because maybe it will assure us of our place in the Premier League next year. If we play at 100% and with the fans behind us, I am sure there will be no problem."
The 23-year-old says one of the key factors in Southampton's recent improvements is that players are no longer afraid to dole out some harsh words to one-another when necessary.
"At that start of the season we didn’t have anyone saying ‘we need to do this’ at certain points of the game," he reveals. "Now we all know what we need to do in certain circumstances.
"We’ve always worked for each other but now, if a player isn’t in a game for some reason, we make sure that we tell him – even if it’s in a rude way or in a way that he doesn’t like.
"At the end of the game, they will come to you and say thanks for making them a bit more alive. In football, you’re not always here to be nice to each other.
"You need to help your teammates and if that needs to be said in a bad way then let’s do it.
"I’m sure if I make a bad pass or I miss a touch, someone will tell me to liven up.
"Maybe at the start of the season we would take it personally because you aren’t confident in yourself, but now everyone understands that it’s done for good reasons."
Our feature interview with Morgan Schneiderlin appears in this tomorrow's matchday programme, available in and around St Mary's priced at just £3.
The Frenchman discusses his five years at Southampton; his decision to stick with the club after relegation to League 1; his journey to become the player he is today; and his ambitions for the future.
The feature also appears in the latest edition of The Southampton Way on iPad, which features a bonus video version of the interview and can be downloaded via the App Store right now.