Klopp's rotation dilemma at Liverpool as Karius shows promise in goal

Roberto Firmino and Mohammed Salah's roles in Liverpool's 2-0 victory at Southampton were celebrated, although such performances become less surprising by the week. Both are having outstanding seasons.

Although they could hardly claim to be under siege it was Liverpool's defence that was scrutinised more. Hardly a surprise, since it is largely considered to be the team's weakness.

Loris Karius did well in goal. Liverpool have been shipping goals lately, with every opposition strike on target seemingly going in.

Southampton's threat fizzled out after Salah made it 2-0 just before the break. In such games it's difficult to gauge if this was a direct consequence of Liverpool's efficiency or not.

Jurgen Klopp won't care. In fact he'll note for the third game running his goalkeeper made an important save to either keep his team in the lead or, as against Huddersfield and Tottenham, on equal terms.

Nothing that could be described as world class or miraculous, but given how things usually go for Liverpool there was enough to justify Klopp's public pronouncement of Karius as his No.1.

With the Champions League returning this week, Klopp can't return to alternating keepers. Even if his countryman were to make a bad error in Porto on Wednesday, he must persist with him.

In December 2016, Karius made errors in a few games -- enough for Klopp to bring back Simon Mignolet. With hindsight, that doesn't appear to have been very patient.

Having promoted Karius again, Klopp tried to do right by the Belgian by giving him a place in the FA Cup team. There were times in that 3-2 defeat at Anfield against West Brom that Mignolet let himself down badly, and any concession to him for what remains of Liverpool's season would be a mistake.

Herein lies the problem with squad rotation. It isn't just about maintaining fitness, it's also about keeping squad players sharp and hungry. You can't just stick to the same XI, as once somebody regards himself as surplus to requirements they'll down tools and be on to their agent looking for a club that does want to use them.

Twice on Sunday, Karius made saves that spared the blushes of his left-back Andrew Robertson, who'd been caught out by long crosses over his head.

Those aside, the Scot is another example of a player who perhaps shouldn't be rotated any longer. Fans feel he's done more than enough to keep his place, and that players like Mignolet and Alberto Moreno have had plenty of chances to stake claims for regular selection.

That may also apply to Dejan Lovren, as patience has worn thin with the Croatian too . Klopp's argument there is that nobody has really stood out in the fight to partner Virgil van Dijk.

The Dutchman himself has only just earned his first Liverpool clean sheet, seeming almost to glide through the Southampton game and smirking whenever the home fans tried to unsettle him.

His £75 million fee guarantees he'll take one of the central defence places on a regular basis, but nobody has stood out yet to be his long-term partner.

As with the goalkeeper, Klopp needs to see out the season with what he currently has at his disposal and gauge if more transfer investment is needed in any position.

At right-back, Klopp has also rotated more than usual, dealing as he is with two young albeit talented players in Joe Gomez and Trent Alexander-Arnold.

Both have done well when selected but also have a propensity for lowered concentration levels -- vital in a defender, but rare in younger players.

Gomez has the edge defensively while Alexander-Arnold is better going forward. In this instance rotation can actually benefit Liverpool as both players are given match experience to suit different opponents. It's just difficult for their colleagues at the back to acclimatise to a different individual on the flank every week.

Liverpool's last two wins have been comfortable, both away against relegation-threatened opposition. That doesn't mean fans didn't appreciate them, given that the previous two defeats were also against sides in the lower depths of the Premier League.

With the season starting to heat up, Klopp may tinker less with his side. It may also mean some players are gradually impressing upon the manager that they shouldn't ever be dropped.

The conundrum now is whether change is necessary to rest tiring players. Porto is a huge game on Wednesday, but there are 10 free days after that because of FA Cup elimination. There'll be plenty of time for rest then.

Liverpool's only chance of a trophy, unlikely as it may already seem, depends upon Klopp making the right choices this week. He's not got a lot wrong so far this season.