COINCIDENCE or not, Fraser Forster’s comeback from injury has gone hand-in-hand with a transformation in Saints’ defence for the better.

Since the goalkeeper's return from a long-term knee injury against Watford, Saints haven’t conceded a goal in three matches.

The home win over Watford was followed by a straightforward 3-0 triumph over West Brom and then an impressive 1-0 win at Manchester United.

In that time Forster hasn’t had to make a single save from inside the penalty area or six-yard box.

In fact, since his comeback, he’s made just two saves in 270 minutes.

That’s one at Old Trafford and one against Watford.

No wonder he’s still feeling slightly rusty.

But that still doesn’t answer why Saints’ defence has been vastly improved since his return.

What is apparent, though, is that Ronald Koeman’s side are not letting opponents anywhere near their goal. 

That could partly be explained by the change in formation, which has them set up with five defenders.

Saints, in recent weeks, have stuck to that 5-2-2-1 formation after playing a 4-2-3-1 for the last season-and-a-half.

When they attack, the wing-backs - Cedric Soares and Matt Targett - burst forward, providing overlapping runs to the forwards and an option on either flank to get crosses in, but then both are covering their respective sides when Saints’ opponents break forward.

It was a formation they tried but failed with during the FA Cup third round defeat to Crystal Palace, but it has worked like clockwork over this three-game winning streak.

And one of the big reasons for that is Ryan Bertrand, who usually operates as a full-back, but has been exceptional at an unfamiliar role at left centre-back. Jose Fonte and Virgil van Dijk have been brilliant alongside him too.

Bertrand was excellent at Old Trafford and, as Forster alluded to, he can pretty much be utilised anywhere on the pitch if called upon.

On top of that, Forster’s communication skills back there must be a huge boost.

Maarten Stekelenburg rarely did anything wrong during his interim spell in Saints’ goal, but were his communication and organisation of the defence as strong as Forster’s?

Perhaps the Dutchman didn’t have the same level of understanding with his backline as Forster.

Since the England stopper returned, the defence looks confident and assured.

Forster worked alongside van Dijk at Celtic and he already has that understanding with Fonte and Bertrand from last season, meaning their working relationship is strong.