Jack Conan fired defending champions Leinster into the quarter-finals of the European Champions Cup with an impressive 29-13 victory over Toulouse on Saturday.

The unrelenting Leinster machine, guided by former player Leo Cullen and ex-England coach Stuart Lancaster, suffocated the free-flowing, offloading game Toulouse have been employing to such success this season. 

The loss was their first since September and brought to an end a 12-match undefeated run.

"We managed possession quite well in the first half. Toulouse had this big wall of defenders the whole time and our guys showed good patience to keep hold of the ball," said Cullen.

No. 8 Conan was at the heart of a stifling home defense that allied seamlessly with a staggering ability to keep hold of possession for minutes on end.

Sean Cronin fires an explosive shot as tailgunner from the lineout.

Big penalty win for Leinster. pic.twitter.com/ikGEkffQgr

— Murray Kinsella (@Murray_Kinsella) January 12, 2019

Ross Byrne, standing in for the injured Jonny Sexton at fly-half and with Rob Kearney, Robbie Henshaw, Devin Toner and Dan Leavy all also missing, kicked an early opening penalty, quickly nullified by Toulouse full-back Thomas Ramos.

A dancing Jordan Larmour break sparked an incredible 38 phases of play for Leinster over more than three minutes in and around the Toulouse 22-metre area, but the visitors, marshalled magnificently by ex-All Black No 8 Jerome Kaino, withstood the pressure.

Cheslin Kolbe was on hand with a fantastic try-saving tackle on sniping Luke McGrath, the diminutive Springbok winger managing to somehow prevent the Ireland scrum-half from grounding the ball from a five-metre scrum.

But Leinster continued to camp out deep in Toulouse territory, Conan finally crossing for the game's opening try on the other wing after a long pass had stretched a scrambling defense.

Byrne converted, but Ramos hit a second penalty at the whistle to leave a tense game 10-6 at half-time at a packed RDS Arena in Dublin.

After the break, winger Dave Kearney soared high to gather a Byrne cross-kick and somehow rode a Romain Ntamack tackle to touch down in the corner.

© Agence France-Presse