Now leading for the first time in the match, Palace took command of the ball as the pace of the game dropped and both managers turned to their benches for refreshed legs.
It was Southampton who found an extra gear going into the final 20 minutes, however, winning a free-kick from which Lambourne tipped substitute Alice Griffiths’ header onto the crossbar.
Palace unfortunately failed to clear their lines, however, allowing the Saints to recycle the ball and Dean – against her former club – to tuck in a loose ball from near the penalty spot amidst a sea of bodies.
The Eagles came forwards once again and forced Southampton ‘keeper Kayla Rendell into a pair of saves from Dennis’ looping cross and Molly Sharpe’s follow-up effort.
But a succession of late Southampton crosses eventually paid dividends for the visitors when Lexi Lloyd-Smith’s in-swinging cross was met by an admittedly impressive glancing header from Katie Wilkinson seven minutes from time, snatching all three points.
Backed by a spirited crowd, Palace pressed for their third equaliser of the match, but could not find the breakthrough as Southampton ran down the clock, in turn ensuring the Eagles’ first home defeat of 2023/24.
Southampton leapfrog Palace into third in the Championship but the standings remain incredibly tight; should the Eagles win their game-in-hand against Sheffield United, they themselves will go top of the table.
Palace: Lambourne (GK), Reilly, Everett, Nolan, Gibbons, Arthur (Filbey, 66), Hopcroft, Potter, Dennis (Bailey-Gayle, 87), Sharpe, Hughes
Subs: Negri (GK), Johnson, Cataldo, Sibley, Guyatt
Southampton: Rendell (GK), Peake, Purfield, Parnell, Mott, Morris, Kendall, Peplow (Primus, 69), Pike (Griffiths, 69), Dean (Lloyd-Smith, 80), Wilkinson (Kraft, 90)
Subs: Howard (GK), Rafferty, Wynne, Milne, Pharoah