Jurgen Klopp undeniably had a selection dilemma going into Liverpool's second-leg of their last-16 tie with Porto on Tuesday evening, having to find a way to respect the opposition without taking too many risks.The 5-0 rout from the away leg had all but put his team into the quater-finals and no one seriously expected much of a game at Anfield.Adding further reason to rest players was the imminent trip to Old Trafford for what could be their biggest game of the season against Manchester United.The clash between the two great rivals is always a big occasion but victory for either team will put them in a great position to finish above the other - about as good as it'll get domestically, considering Manchester City's domination of the league.So the game against Porto represented a fantastic opportunity to rest the key players - not that Klopp exactly took it.The Liverpool boss did leave out star player Mo Salah, but the likes of Roberto Firmino, Sadio Mane, captain Jordan Henderson, and Emre Can all started despite all being likely starters against United.And then, to confuse matters more, Klopp introduced Salah with fifteen minutes to go; Liverpool fans weren't too happy with the manager risking their Egyptian king.Check out the response to Salah's introduction below:

But speaking after the game, Klopp revealed a pretty good reason for bringing Salah on, explaining that he'd made a deal with the player.

“It is normal. Everyone thinks about injuries but that can happen all the time,” Klopp said.

“Now we thought we give him, if possible, the last 20. If it is 15 he trains again tomorrow.

“I told him if he really runs a lot he does not have to train tomorrow so I thought he was quite lively.”

One worry for fans after the game was Henderson walking around with an ice back on his leg, but Klopp confirmed that it was nothing serious.

"Dead leg," he explained. "Just painful enough but not a problem."

Things appear to have worked out for Klopp then, depsite what many saw as a risk. He managed to hand games to a bunch of players on the fringe of the starting eleven, while giving a relatively relaxed run out to his stars.

It could prove vital as the Reds enter an incredible important time in their recent history.

With eyes on second place and a Champions League quarter-final coming up, this may be a pivotal season for Klopp at Liverpool.