Manchester United are well-stocked at the back.
David Moyes can call on the experience of Rio Ferdinand and Nemanja Vidic at centre-half, or the growing talents of Jonny Evans, Chris Smalling and Phil Jones.
Rafael has made the right full-back position his own while, Patrice Evra rediscovered something like his best form at left-back last season.
Fabio is back from his loan spell at QPR to provide cover on the left or the right, while Alex Buttner was brought in last summer to offer a challenge to Evra's place.
But it hasn't stopped United being linked with reinforcements. United have been linked particularly with Everton's Leighton Baines, as reported by The Guardian's Andy Hunter. Benfica's Ezequiel Garay has also been strongly linked with the Red Devils, with Charles Perrin of the Express going as far as reporting that an agreement had been reached earlier this month.
But which defenders would improve United's defence, and which ones might Moyes be interested in?
David Moyes knows all about Leighton Baines from their time spent together at Everton.
The 28-year-old was linked with a move to Old Trafford last summer after some indifferent performances from first-choice left-back Patrice Evra.
At 32, Evra is going to need replacing sooner rather than later, but United fans would argue that the money might be better spent on a midfielder this summer.
Ezequiel Garay has been linked with a move to United for more than a year.
The Argentinian former Real Madrid defender is highly rated in Portugal, where he plays for Benfica, and in Spain but it's difficult to see where he fits in to a defensive unit that already includes Rio Ferdinand, Nemanja Vidic, Jonny Evans, Chris Smalling and Phil Jones.
At 26, it's unlikely David Moyes would shell out to have him sit on the bench.
A Rolls-Royce of a defender, Mats Hummels has forged a reputation as one of the premier ball-playing centre-halves in the world.
The 24-year-old, with a look of Jurgen Kohler and a style on the ball reminiscent of Franz Beckenbauer, was part of the Borussia Dortmund side that were beaten finalists in the Champions League last season.
But any interest United might have in the future is likely to be rivalled by Barcelona, that is if the German isn't prised away to the Nou Camp this summer. This report from Goal.com's Alec Fenn tells of the German's flattery at the interest of the Spanish club.
Signed by Tottenham from Ajax last summer, Jan Vertonghen was one of the Premier League's success stories last season.
It's the Belgian's flexibility that would make him most appealing to United if and when they begin the search for a new defender, with the 26-year-old comfortable at centre-half or at left-back.
United might have already missed their chance to sign Raphael Varane after coming close to taking him to Old Trafford when he left Lens in 2011.
That was until Zinedine Zidane stepped in on Real Madrid's behalf and in the last two years the Frenchman has become one of the most highly-rated young players in the world.
He ousted Pepe from the first-team last season and at just 20, he's only going to get better. He's perhaps best filed under "the ones that got away."