Celta Vigo were 1-0 victors over fourth placed Sevilla during the weekend’s La Liga action, with Saints loanee Sofiane Boufal involved in 80 minutes of the encounter.
Central midfielder Okay Yokuslu netted the game’s only goal in the 73rd minute, as Celta edged a point clear of the drop zone.
Elsewhere on the continent, Jordy Clasie’s Feyenoord lost out 2-1 to Excelsior, having initially taken the lead.
Robin van Persie had fired Giovanni van Bronckhorst’s side ahead early in the second period, but Robin Van der Meer had the final say in stoppage time, adding to Ali Messaoud’s 63rd minute strike.
Feyenoord, who are chasing down leaders Ajax and PSV Eindhoven, now have an 11 point deficit to make up on the former, and a 16 point gap between themselves and PSV.
Back in England, Jake Hesketh’s MK Dons debut ended in disappointment, with a 3-1 defeat away to Exeter.
Hesketh replaced Ryan Harley in the 55th minute, but ultimately the damage had been done first half, where goals from Nicholas Law and Jake Taylor gave the hosts a 2-0 lead before the break.
The Dons, led by former Saints Paul Tisdale, remain within League Two’s play-off spots, but are now level on points with Exeter.
Harry Reed’s Blackburn suffered similar fate away to Brentford in the Championship, succumbing to a 5-2 loss.
Tony Mowbray’s side had raced into a 2-0 lead, with only seven minutes on the clock. Bradley Dack was on target for the opener, followed up by Danny Graham’s 11th of the campaign - teed up by Reed himself.
But Rovers were opened up thereafter, shipping five goals in the remaining 80 minutes, and suffering their first league loss of 2019.
In Non-League, Ben Rowthorn and Truro City registered a 2-0 success over Eastbourne Borough in the Vanarama National League South.