United have already dropped 10 points this season as Louis van Gaal's new-look side struggled to gel in the early stages of the campaign.
It had been suggested that the Premier League giants were a declining force, but Van Gaal has since welcomed a raft of big-name talent to Old Trafford to the tune of £150m.
The Red Devils have strung together back-to-back wins against West Ham United and Everton respectively, and Irvine urges his troops to be mindful of their quality.
"They are still Manchester United and have some great players," Irvine told Sky Sports News ahead of tonight's clash at the Hawthorns. "It's going to be a huge game for our club, players and fans.
"They have been a fantastic team over the years but the squad was looking like it was going to need some changes and I read something from Sir Alex Ferguson saying it has needed an overhaul.
"Manchester United have been dominant for many years so they are eventually going to have to change and that's the situation they are in at the moment."
Kickoff tonight is scheduled for 8pm.