Charlie Austin scored twice and Jay Rodriguez netted one of his own in added time for Southampton to give the club their first win in Europe following a 13-year absence.
Claude Puel’s side ran out 3-0 winners at St Mary’s in their Europa League Group K clash against Costa Nhamoinesu’s Sparta Prague, who reached the quarter-finals of the competition last season.
Sparta’s Costa was penalised for a handball in the first minute, but there was not much that the defender could do about it as the ball bounced off his leg and onto his arm during a tackle on Austin.
Initially, referee Manuel Grafe awarded a free kick on the edge of the box, but he switched to a penalty after discussing the incident with his linesman.
Elsewhere, Tonny Vilhena scored the only goal of the match as Feyenoord recorded a 1-0 win over Manchester United in Thursday night’s Europa League clash in Rotterdam.
A drab 90 minutes saw both teams struggle to create opportunities, but Man United lost a second successive match after Vilhena found the bottom corner with a smart finish in the 79th minute of the Group A fixture.
Man United boss Jose Mourinho made eight changes to the team that started the Manchester derby at the weekend, with only David de Gea, Eric Bailly and Paul Pogba keeping their spots in the XI.
Marcus Rashford came into the team at centre-forward, while Matteo Darmian, Chris Smalling, Marcos Rojo, Morgan Schneiderlin, Ander Herrera, Juan Mata and Anthony Martial were all given chances to impress as Luke Shaw, Antonio Valencia, Wayne Rooney and Henrikh Mkhitaryan were left at home.