NEWS of injury scares for Jozo Simunovic and Mikael Lustig arrived during the international break, raising concerns once again about Brendan Rodgers' sparse defensive options at Celtic

While neither player appears to have picked up a major problem, the Northern Irishman has already been stretched this season with the likes of Simunovic, Dedryck Boyata and Erik Sviatchenko all facing spells on the sidelines.

Boyata is now back and Sviatchenko is returning to fitness, but the Scottish champions could do worse than considering options in the free transfer market if another injury crisis rears its head.

Read more: Popped shoulder not enough to stop Celtic youngster Kristoffer Ajer​

Here is a selection of some of the biggest names available at the moment – could any of them cut it at Parkhead?

Sebastien Bassong

The 31-year-old has bags of experience on his CV, but is still without a club despite spending the opening months of the season training with Birmingham City.

After starting his career in French football with Metz, Bassong has plied his trade in England ever since with Newcastle United, Tottenham Hotspur and Norwich City as well as loan spells as Wolves and Watford.HeraldScotland:

A Cameroon international, Bassong represented his country at the 2010 World Cup and has made 177 Premier League appearances during his career. However, his time at Norwich was brought to an end in the summer when he was released after making just nine league outings.

Joleon Lescott

Another experienced Premier League defender, Lescott almost made the move to Scottish football last summer when he came close to joining Rangers before opting out due to family reasons.

Whether he would be willing to make the move north a year later is a question that Rodgers would need to address, particularly now that the 35-year-old has landed a cushy job on the Sky Sports pundit sofa.

Read more: Popped shoulder not enough to stop Celtic youngster Kristoffer Ajer​

But with 26 England caps, two Premier League titles, an FA Cup and a League Cup on his honours list, the former Everton, Manchester City and West Bromwich Albion stopper remains one of the most decorated free agents on the market.

He has been training with non-league side AFC Telford to keep fit while hunting for a new challenge. 

Marcin Wasilewski

No-nonsense Poland international Wasilewski played his part in football history when he helped Leicester City win one of the sport’s most surprising league titles two years ago.

Although he played second fiddle to Wes Morgan and Robert Huth throughout that campaign, the 37-year-old is an available option with top-flight and international experience.

The former Anderlecht man has racked up 60 caps for his country, representing them at two European Championships finals, but will be short of match fitness after making just seven appearances last season before being released in the summer.

Kelvin Wilson

A familiar face, Wilson spent two seasons at Parkhead between 2011 and 2013, winning two league titles and a Scottish Cup in the process.

He has been performing in the English Championship since then, spending three seasons at Nottingham Forest before an unsuccessful spell at Rotherham United last term. His deal at the club wasn’t extended following their relegation and at the age of 32 Wilson will feel he still has much to offer.HeraldScotland:

The former Celt has a worrying injury record and spent more time on the sidelines last season, but a reunion could be tempting for both sides with the defender looking to get his career back on track and the Hoops in need of reliable defensive cover.

Joel Ekstrand

A teammate of Wilson’s at Rotherham during the second half of last season, Ekstrand has also failed to pick up a new club since his release.

Although he has no experience of Scottish football, the two-time Sweden international has spent the last four years in England with Watford, Bristol City and the Millers and is still only 28 years old.

Another who has been plagued by injury problems, to his hamstring last season and previously to his knee and cruciate ligament while at Watford, he represents a riskier option if the Bhoys dip into the free transfer market.