Southampton held off Portsmouth to secure a 1-0 Championship victory at St Mary’s, earning their first league win over their Hampshire rivals in almost 22 years.
James Bree scored the decisive goal before Cameron Bragg’s dismissal left Saints playing with 10 men for the entire second half.
The hosts responded with a determined defensive display to protect their advantage and climb to 11th in the table.
It was Tonda Eckert’s first match since receiving a suspended six-week ban and a £28,000 fine from the Football Association for his involvement in the Spygate scandal.
Southampton have continued to support their head coach, and his players delivered a resilient performance in a fiercely contested derby.
Portsmouth showed early promise, with Ryan Kavuma-McQueen driving into the right side of the penalty area before firing a powerful effort across goal.
However, Southampton took the lead when Finn Azaz lifted a precise pass into the path of Bree’s run towards the far post.
The defender controlled with his right foot before finishing into the bottom corner with his left.
Saints’ position became more difficult shortly before half-time when Bragg pulled down Ebou Adams and received his second yellow card.
The academy graduate was visibly upset as he left the pitch, with Leo Scienza and Eckert offering reassurance.
Despite their numerical disadvantage, Southampton created an excellent opportunity to double their lead soon after the restart.
Scienza broke through on goal, but Nicolas Schmid produced a superb save.
The hosts appealed for handball from the resulting corner, only for referee Adam Herczeg to dismiss their penalty claims.
Tensions increased before the hour when Azaz was booked for a heavy challenge on Adams.
Portsmouth players argued that the foul deserved a stronger punishment, sparking a confrontation between the sides.
Pompey pushed for an equaliser, but Southampton remained compact and restricted the visitors’ clear chances.
Substitute Marko Milovanovic came close late on, meeting a cross from the left but sending his effort into the side netting.
Azaz once again made a telling contribution in the south coast derby, following his influential display at Fratton Park last season.
His assist took him to nine Championship goal contributions in Southampton’s opening nine matches of the campaign.
Eckert’s tactical adjustment also paid off.
Saints moved away from their usual 4-2-3-1 towards a 4-1-4-1 shape, allowing Bree to advance into dangerous positions on the right.
The defender exploited that freedom for the winning goal, timing his run well before producing a composed finish.
After Bragg’s red card, Southampton shifted their focus to defending their lead.
Their discipline and organisation frustrated Portsmouth throughout the second half.
Portsmouth had an opportunity to draw level in the closing moments of the first half but could not capitalise on having an extra player.
John Mousinho’s side controlled much of the possession after the interval, regularly working the ball wide and looking for cut-backs or shooting opportunities around the edge of the box.
Abu Kamara and Tyrese Shade occasionally beat their markers, but the quality of their final delivery let them down.
Kamara also had efforts blocked after moving inside on to his left foot, with Southampton’s defence repeatedly closing down the space.
The defeat leaves Portsmouth 19th after eight Championship matches, just one point above the relegation zone.
Speaking to BBC Radio Solent, Eckert described the derby as Southampton’s biggest match of the season so far and stressed the importance of securing the result.
He acknowledged that his players had been forced to defend for long spells, while pointing to Scienza’s chance early in the second half as an opportunity to make the closing stages more comfortable.
With a trip to Norwich coming on Wednesday, Eckert said there was still more to come from his side.
Mousinho told BBC Radio Solent he was deeply disappointed by the defeat, particularly given Portsmouth’s numerical advantage and the promising positions they reached.
He felt his players made useful runs behind Southampton’s defence, especially down the right, but too often failed to deliver an effective cross after reaching the byeline.
Although the substitutes made a positive contribution, Mousinho admitted Portsmouth had not done enough to score and would regret the opportunities they wasted.
