Patrick Bamford's 16th goal of the season and a first Premier League strike from Tyler Roberts ensured that Marcelo Bielsa's Whites recorded a third consecutive victory for the second time this season.
The win put Leeds on to 56 points for the campaign and Graham Smyth, the YEP's chief football writer, hands out the scores from the display at St Mary's.
1. Kiko Casilla
7 - A couple of big saves, some poor distribution that put defenders in a tight spot and a few flaps at corners, but a lovely pass for the second goal. Photo by Peter Powell - Pool/Getty Images.
2. Luke Ayling
6 - A poor start to the game aside he dug in, defended stoutly and produced his finest 'flop' of the season. Photo by Catherine Ivill/Getty Images.
3. Liam Cooper
6 - Struggled with his passing but a lot of it was done under pressure. Made some big challenges in the second half. Photo by Stu Forster/Getty Images.
4. Diego Llorente
7 - Showed good aggression and reading of the game in the first half. Tried to get Leeds going with his passing. Replaced at the break by Bielsa. Photo by Naomi Baker/Getty Images.
5. Kalvin Phillips
6 - Looked frustrated as the Saints got the better of the midfield and he was left chasing. Once he was on a yellow replacing him was sensible. Photo by Lee Smith - Pool/Getty Images.
6. Stuart Dallas
7 - Steady. Didn't start well but in the second half produced some good link-up play and very nearly scored a wondergoal. Photo by Michael Regan/Getty Images.