Liverpool will have to make do without Virgil van Dijk for most of the 2020/21 season.
The Dutchman has been ruled out for an indefinite period of time after sustaining a serious knee injury in last Saturday's Merseyside derby versus Everton.
Van Dijk's prolonged absence is a hammer blow to Liverpool's aspirations for the campaign and Jurgen Klopp's team now have just two senior centre-backs left in Joel Matip and Joe Gomez.
Fabinho can fill in at the back, but the Brazilian's best position is at the base of the Reds' midfield and Klopp will be reluctant to remove him from that role on a permanent basis.
But the Liverpool boss may not have a choice, unless the club decide to sign a new centre-back on a free transfer.
The transfer window may have closed, but those who are free agents can still be snapped up by teams across the world and there are a few options the Reds could turn to.
Below, we've provided the nine most valuable centre-backs in the world right now who are available for free. Market values courtesy of Transfermarkt.
9. Ashley Williams
Age | 36
Market value | £1.08m
He might still be Wales' captain, but Williams is currently without a club after leaving Bristol City at the end of last season. Would Liverpool dare turn to a former Everton man in a moment of crisis? Well, they could certainly do worse...
8. Fernando Tobio
Age | 31
Market value | £1.08m
The Argentine central defender spent both the 2015/16 and 2016/17 seasons on loan at Boca Juniors and he also made nine appearances for Argentina's U20 side. Tobio's most recent team was Deportivo Toluca in Mexico, where he played 45 games and scored two goals.
7. Joel Lynch
Age | 33
Market value | £1.08m
Yeah, we can't see this one being a goer. During the early stages of his career with Brighton, Premier League clubs were keeping tabs on Lynch, but now 33, he's yet to play a game in the English top-flight. His underwhelming spell at League One Sunderland in 2019/20 means a move to Liverpool just isn't going to happen.
6. Adrian Mariappa
Age | 34
Market value | £1.44m
The Jamaican defender left Watford this summer after four years with the club, making 20 Premier League appearances for the Hornets in 2019/20. Over the last three years, Mariappa has played 74 games in the English top-flight, so he'd probably be a decent short-term option for Klopp.
5. Andre Pinto
Age | 31
Market value | £1.71m
The Portuguese centre-back has had stints with FC Porto, Braga and Sporting Lisbon throughout his career, with his most recent playing spell coming at Saudi Arabian side Al-Fateh in 2019/20. A regular in Portugal's youth teams and one cap to his name for the country's senior team, Pinto's CV is pretty impressive.
4. Jozo Simunovic
Age | 26
Market value | £1.98m
The only player of the nine under 30-years-old, Simunovic spent the last five seasons of his career at Celtic, making 126 appearances in all competitions for the Scottish side. Six of those appearances came in the Champions League, so maybe the Croatian has what it takes to play at the very highest level for Liverpool.
3. Ryan Shotton
Age | 31
Market value | £2.16m
The former Stoke City man had been a regular at Middlesbrough before leaving the club this summer. Capable of playing right-back, centre-back or as a makeshift centre-forward, Shotton has already made 48 Premier League appearances during the course of his career.
2. Daniel Schwaab
Age | 32
Market value | £2.52m
A former Germany U21 regular and a key member of Die Mannschaft's squad that won the U21 European Championship in 2009, Schwaab has spent the last four seasons in Holland with PSV. He's made 16 appearances in the Champions League throughout his career, with five of those coming in 2018/19.
1. Ezequiel Garay
Age | 34
Market value | £4.32m
Surely Garay is a player Liverpool should be - at the very least - looking at, right? The Argentine left Valencia in the summer after four years with the club and he was widely regarded as one of La Liga's finest defenders during that timeframe. Garay also has 34 Argentina caps under his belt and was part of the country's 2014 World Cup squad.
The former Real Madrid and Benfica man has all the experience needed to provide Liverpool with a much-needed boost at the back for what's to be a seriously hectic domestic season.