The two sides meet in the Europa League on Thursday.
The two sides meet at Anfield on Thursday in arguably the pick of this round of fixtures.
It is the first time they have ever met in a European competition, with both keen to progress and secure the Champions League place on offer to the winners.
As always with this fixture, which has continually been a heated affair, emotions are likely to be charged, and Fowler has warned his old team to control their emotions in the game.
A few of the players have come out and said they owe the fans and they probably do, to be fair,” he told Liverpoolfc.com.
"But they've got to try and control the emotions because it is a big game, a big European game - probably the biggest game the Europa League has ever had.”
"There are going to be all eyes on it, so the players do really need to control their emotions; we don't want silly cards or silly red cards because we want to be on top of our game with full-strength team."
How both sides approach the game will be a clear indication of what their focus will be during the end of this season.
Going with strong sides will show that their focus is likely to be on winning the tournament, but rotated sides could hint they are still focused on a top four place.
That is certainly still within their grasp as they sit three and six points away respectively, and it will be interesting to see how where Klopp and Van Gaal will focus most.