Cardiff Devils' lead at the top of the Elite League was cut to two points as they were beaten 5-4 at home by the second-placed Sheffield Steelers.
The Devils had claimed their first victory at Sheffield since 2012 on Saturday, winning 4-3.
They took the lead in Cardiff as well but fell 2-1 behind as Tyler Mosienko and Conny Stromberg struck.
The Devils levelled at 2-2, 3-3 and 4-4 but the Steelers snatched victory with another goal from Mosienko.
That took Mosienko's weekend tally to five goals, having scored a hat-trick in the Steelers' home defeat to the Devils on Saturday.
The Devils' next match is a trip to Belfast for the second leg of their Challenge Cup tie.