Adam Armstrong bagged another brace as a confident Southampton side made it six wins in seven matches under Tonda Eckert, despite a very nervy finish.
West Brom arrived on the South Coast two points below their hosts in the Championship table and without a win on the road in six outings. With Ryan Mason under mounting pressure, Southampton showed no sympathy.
Leo Scienza gave the Saints an early lead when he drove home a right-footed shot after eleven minutes. Great work from Tom Fellows in the build up gave the Brazilian time to pick his spot in the far corner.
Six minutes later, Adam Armstrong extended Southampton's lead when he took advantage of a mistake in the Baggies' defence. Nathaniel Phillips dwelt on the ball for a moment too long on the edge of his own penalty area. When Adam Armstrong easily robbed the ball off him, there was only going to be one outcome.
Adam Armstrong took his goal tally for the season to 11 when Finn Azaz turned delightfully and guided his through ball into Armstrong's path. Having scored once already, the 28-year-old found the far corner with a low shot from a tight angle.
West Brom pulled one back on the hour when Karlan Grant took advantage of some poor Saints defending. Léo Scienza allowed Grant to run past him on the edge of the box before driving in a left-footed shot past Bazunu.
Baggies defender Nathaniel Phillips made up for his mistake in the first half with a goal of his own in the 86th minute to set up a nervy finish.
Full-Time: Southampton 3-2 West Bromwich Albion
Southampton player ratings:
Gavin Bazunu (GK) - 7/10 - Another good performance from Bazunu. Made some important saves in the final 10 minutes as the Baggies pressed for a second goal.
Taylor Harwood-Bellis (RCB) - 8.5/10 - The former England international must be enjoying his football as much as he has ever done. Defensively he was very sound again, but he was at his best with the ball at his feet tonight. Given licence to advance with the ball in the first half, he was instrumental in the build up for two of the Southampton goals.
Nathan Wood (CB) - 7/10 - Put his body on the line to keep the Baggies out in the first half. Good positioning throughout. His best performance in recent weeks.
Joshua Quarshie (LCB) - 7/10 - Completed 100% of 47 passes in the first half and he looked comfortable again in place of the captain. He must be wondering what more he needs to do to start even more regularly under Eckert.
Tom Fellows (RM) - 7/10 - Given more opportunities to attack than on Saturday against Birmingham on Saturday. His brilliant 40-yard run with the ball and exquisite pass for Scienza's goal was worth the entrance fee alone. Replaced by Ryan Fraser after an hour.
Flynn Downes (CM) - 7/10 - Pressed hard against the ball and dominated the midfield. Could do better with his passing accuracy but that's not what he is in the team for. Kept going all night.
Caspar Jander (CM) - 7/10 - More advanced than Downes in the early stages but dropped alongside his midfield partner the more that Harwood-Bellis and Fellows advanced down the right. Read the game well but faded late in the second half.
Ryan Manning (LM) - 6/10 - Wasteful in possession again. This was not Manning's best day at the office. His dead-ball delivery was poor in the first-half.
Léo Scienza (LF) - 7/10 - A direct run at the West Brom defence drew a foul and a yellow card for Ousmane Diakité as early as the 8th minute. Finished brilliantly for Saints' opener after Tom Fellows had dribbled through the entire West Brom midfield. Withdrawn after an hour.
Adam Armstrong (CF) - 8.5/10 - Showed his intentions early when he stung the keeper's hands in the 5th minute with a powerful left-footed drive from the edge of the penalty area. Took advantage of a mistake in defence for Saints' second goal. Withdrawn with 15 minutes to go.
Finn Azaz (RF) - 6.5/10 - The assist for Adam Armstrong's second was sublime. His turn was tight and his awareness of Armstrong's run was other worldly. Weighted the pass perfectly. Drifted out of the game in the second half.
Substitutes:
Ryan Fraser - 5/10 - Struggled to deal with Kaylen Grant's pace and made very little impact going forward.
Cameron Archer - 5/10 - Ran around a lot but lacked quality. Went missing in the last ten minutes.
Jay Robinson - 5/10 - Made little difference. Weak in the challenge.
Joe Aribo - 5/10 - Made an effort but added nothing.
Oriol Romeu - 6./10 - Added some much needed stability.