London - Bargain midfielder Pedro Obiang ruined a goalscoring debut for Southampton's new Italian international Manolo Gabbiadini as West Ham United grabbed a 3-1 win on Saturday.
Gabbiadini scored with his first shot for his new club, just 12 minutes into his debut after his £14 million move from Napoli.
The ball was crossed over the West Ham defence and the 25-year-old escaped the offside trap to crash the ball in with his favoured left foot off the crossbar.
But Slaven Bilic's side, who included £10 million import Robert Snodgrass, stunned the home crowd to silence within two minutes.
Obiang, who cost less than £5 million when signed two years ago, split the Southampton defence with a brilliant pass and Andy Carroll powered the ball in for his fourth goal in four games.
While Gabbiadini threatened more trouble, Obiang again stole the limelight just before half-time with his first goal in 55 games for West Ham.
The Spanish player picked up the ball just inside the Southampton half, ran with it and powered a shot from just outside the penalty area that Saints goalkeeper Fraser Forster could not push clear.
West Ham delivered a killer blow just after the break when Mark Noble's corner went into the goal off the boot of Saints midfielder Steven Davis.
Southampton, already without key defender Virgil Van Dijk, suffered a new injury blow when record signing Sofiane Boufal hobbled off with the help of the Saints medical team.
Gabbiadini fired one close chance wide and James Ward-Prowse forced West Ham goalkeeper Darren Randolph into a quickfire tipover.
But the Irons held on for a crucial win that lifted them further into mid-table safety while Southampton must now find a way to avoid falling into the Premier League relegation scrap.