Former Crystal Palace manager Sam Allardyce has queried Jurgen Klopp's decision not to end Mamadou Sakho's first-team exile on Merseyside, praising the player's previous loan stint at Selhurst Park and arguing that he could be the solution to Liverpool's current defensive frailties.

Sakho has not made a single competitive appearance under Klopp since April of last year and was sent home from a pre-season tour of the United States for off-field reasons. He was later banished to the Under-23s before being permitted to join Palace on loan for the rest of the 2016-17 season on January deadline day.

The French international thrived in south London, earning a player-of-the-year nomination despite a knee injury that ended his stint after only eight matches but which still helped the Eagles to avoid relegation to the Championship.

Sakho was widely expected to leave Liverpool on a permanent basis this summer and has yet to feature for the club in 2017-18, although calls for his return are likely to grow louder after the club's defensive issues were further exposed during a two-legged Champions League play-off tie against Hoffenheim and a high-scoring Premier League draw at Watford.

"So they're not going to give Mama Sakho a chance to resurrect his career at Liverpool then, no? No?," Allardyce said on talkSPORT during a discussion centred around the glaring need for Klopp to sign a new centre-back before next week's transfer deadline.

"He was fabulous for me honestly, he was outstanding. One of the reasons we stayed up at Palace was Mama's defensive qualities in the time he spent with us. He turned around what was a very leaky defence.

"They [Sakho and Klopp] fell out I think a long time ago. When he arrived with us, he'd been with the Under-23s [for] the entire season. With great credit to him, [he] comes straight into the side and started from day one performing at the highest level. He was very good."

Palace were said to retain an interest in securing a permanent deal for £30m-rated ($38.4m) Sakho despite Allardyce's surprising departure, although new boss Frank de Boer recently reiterated that he was "much too expensive". West Bromwich Albion are also rumoured to be keen as they prepare for the likely departure of Jonny Evans to Manchester City, while Southampton, West Ham United, AS Roma and Napoli have all been linked at various stages.

Virgil van Dijk speculation

Despite Klopp's public claim that he does not necessarily need to sign a new centre-back with the much-maligned Dejan Lovren, Joel Matip, Ragnar Klavan and Joe Gomez all available, Liverpool continue to be linked with a potential move for wantaway Southampton captain Virgil van Dijk.

The Dutch defender continues to train alone after making clear his desire to move on and recently handed in a transfer request to go along with a fiery public statement in which he implored the Saints to "consider the interest in me from top clubs should it still exist". Liverpool are no doubt having to tread carefully in that particular pursuit having issued a public apology back in June amid reports that they were about to be reported to the Premier League over an alleged illegal approach.

Mamadou Sakho
Mamadou Sakho proved an enormous hit during his short spell at Crystal Palace last season GLYN KIRK/AFP/Getty Images