Chelsea had been looking to re-open their five-point advantage over fifth-placed Arsenal, but the Blues struggled against a well-organised Saints defence.
Find out how all of the action unfolded in West London courtesy of Sports Mole's minute-by-minute updates below.
CHELSEA SUBSTITUTES: Caballero, Zappacosta, Christensen, Emerson, Ampadu, Fabregas, Loftus-Cheek
SOUTHAMPTON SUBSTITUTES: McCarthy, Stephens, Ramsey, Slattery, Elyounoussi, Long, Austin
Southampton only remain out of the relegation zone on goal difference, but victory at Stamford Bridge could take the Saints as high as 15th position.
CHELSEA XI: Arrizabalaga; Azpilicueta, Rudiger, Luiz, Alonso; Kante, Jorginho, Barkley; Willian, Morata, Hazard
SOUTHAMPTON XI: Gunn; Yoshida, Vestergaard, Bednarek; Soares, Romeu, Ward-Prowse, Valery; Armstrong, Redmond, Ings