A first half goal from Jamie Douglas secured a vital victory for Dungannon Swifts as the Blues crashed to their first league loss in 13 games.
Douglas struck in the 37th minute, receiving a pass from Johnny Topley before beating the goalkeeper with a shot which took a big deflection off a defender.
Linfield hit the crossbar through Brian McCaul in the first half, but otherwise they created little for most of the game.
Only in the final 10 minutes did they offer any real pressure.
Conor McMenamin’s low strike was deflected behind by Niall Morgan while Aaron Burns headed off wastefully target from six yards.
DUNGANNON SWIFTS: Morgan, Grieve, Lowe (Brennan, 82), McCaffrey, McMinn, Hazley (S Lavery 77), Topley, Hutchinson, Douglas, Boyce, McCullough. Subs not used: Fitzpatrick, Harpur, C Lavery
LINFIELD: Tuffey, McVey, Waterworth, Lowry, BJ Burns (Ervin, 21), A Burns, Ward, Clarke (McMenamin, 75), Tipton (McAllister, 55), Mulgrew, McCaul. Subs not used: Knowles, Glendinning
Referee: Vadims Direktorenko (Latvia)