And the Anfield Supremo is wary of Town repeating the trick in their Premier League encounter tomorrow afternoon.
“In the Man United game they changed their style completely, they didn’t even play like this against Tottenham Hotspur,” Jurgen Klopp said.
“Against United they parked the bus and won the game.
“Probably, that could also be the way they try to play here.”
The close friendship between the former Dortmund duo has dominated the build-up to their meeting and the pair famously share tactical philosophies.
It therefore comes as a shock Klopp branded his best man as using defensive tactics in the finest win of his managerial career to date.
Wagner spoke proudly yesterday of his team's performance in the 2-1 defeat of the Red Devils.
"Such a result with such a performance gives everybody a boost and confidence for what we have to do in the future," Wagner said.
"It helps massively, every single player, and everyone at the club to believe and trust everything we're doing."
The Anfield chief did go on to praise the squad his former Mainz team-mate has assembled.
“If they have the ball, they are really creative. I knew that from last year,” added Klopp.
Klopp also moved to dampen lunchtime rumours key playmaker Philippe Coutinho would be ruled out of tomorrow’s game.
“Last week he had back problems but we could treat it and he played at Tottenham,” he said.
“This week he had a little problem. It’s not clear whether he is out for tomorrow.”