Leinster trailed to Jack Carty's third-minute penalty, but Garry Ringrose and Sean Cronin crossed in the second half before Robertson-McCoy was involved in an incident that could lead to a lengthy suspension.

The Connacht prop trod on prone Leinster star Van der Flier's head and was dismissed 10 minutes from time, having only been on the pitch a matter of seconds.

While Leinster has a five-point advantage at Conference B's summit, Glasgow Warriors is three points clear of Ospreys at the top of Conference A.

The Warriors were 29-13 winners over the Dragons, Lee Jones scoring either side of the interval to set in motion a relatively comfortable triumph.

Sam Davies's boot made the difference for Ospreys as it required just a single Luke Morgan try to defeat Zebre 22-8.

Scarlets, runner-up last term, is Leinster's nearest challenger in Conference B after winning big against Southern Kings.

Jonathan Davies scored two of eight tries in a 54-14 success, while Munster went one better with nine as it triumphed 64-7 over Ulster.