Leo Scienza’s deflected seventh-minute strike proved the difference at St Mary’s as Saints warmed up for Sunday’s south-coast derby at bitter rivals Portsmouth with an overdue success.

The hosts wasted a series of chances to make the scoreline more comfortable before hanging on to climb a place to 15th position, above Swansea on goal difference.

Chris Wilder’s Blades almost snatched a late leveller through substitute Patrick Bamford but remain 17th – four points above the relegation zone – after slipping to a third-successive defeat in all competitions.

The two clubs started the season among the promotion favourites but beyond the midway point, both are languishing in the bottom half of the table.

Saints boss Eckert made four changes following Saturday’s 2-1 home loss to Hull and watched his team take an early lead.

Brazilian left-back Welington – one of those recalled – dispossessed Ki-Jana Hoever deep in opposition territory, allowing compatriot Scienza to drive towards the 18-yard box and find the bottom-left corner via a hefty touch off Blades captain Ollie Arblaster to claim his first goal in nine games.

Saints striker Ross Stewart threatened with a header and team-mate Tom Fellows was denied a penalty following a challenge from Harrison Burrows before the hosts squandered a golden opportunity to double the lead.

After Arblaster failed to control Callum O’Hare’s pass in midfield, Stewart and Flynn Downes combined to tee up Finn Azaz but he scuffed the ball wastefully wide from eight yards out.

United breathed another sigh of relief four minutes short of half-time when goalkeeper Michael Cooper prevented Scienza capitalising on a slip from Hoever and Burrows blocked the follow-up.

Blades manager Wilder had switched his entire defence as part of seven alterations after his side received two red cards in Saturday’s 1-0 defeat at Charlton, but initially resisted further changes following a poor first-half display.

The visitors gradually began to put some pressure Southampton’s backline, albeit home goalkeeper Daniel Peretz was not significantly tested.

Saints substitute Adam Armstrong – linked with a transfer this month – nodded wide from Elias Jelert’s cross at the other end before Cooper superbly repelled Scienza’s diving header.

Wilder brought on former Southampton striker Danny Ings for the final 11 minutes in a bid to find an equaliser.

Fellow Blades replacement Bamford nearly grabbed an 89th-minute equaliser but he was denied by the legs of Peretz following a defensive mix-up, while Gustavo Hamer headed into the side-netting in added time.