Krisnan Inu and Rhyse Martin both scored late tries as Salford Red Devils and Leeds Rhinos earned victories over St Helens and Castleford Tigers respectively in Monday's Super League games.
In a repeat of last season's Grand Final, Saints fielded an inexperienced side, naming five debutants with one eye on their forthcoming derby with Wigan, but the gamble backfired as they suffered a 12-10 defeat.
A try from Josh Eaves and three successful kicks from Lewis Dodd had given Saints a 10-0 lead as the leaders went in search of an 11th victory on the spin.
But Salford roared back with a try from Pauli Pauli before Inu muscled his way over the line before converting his own try to secure the win.
Martin's converted try ensured Leeds clinched a 28-24 Yorkshire derby win despite a late Castleford fightback with Oliver Holmes shown a red card for the Tigers.
Tries from Ava Seumanufagai, Luke Gale, Liam Sutcliffe and Tom Briscoe proved decisive for Leeds, as a late penalty score for Castleford was supplemented by two tries from Greg Eden plus one from Liam Watts.
Leeds – who are chasing a play-off spot – sit fifth in the standings, with two games against Wakefield Trinity to come this week.