Saracens got off the mark in the Investec Champions Cup with a 55-36 win over Connacht in a 13-try thriller at the StoneX Stadium on Saturday.

Olly Hartley crossed twice in a frantic second half as the Premiership champions ran in eight tries in total.

Connacht's five tries ensured they left with a losing bonus point.

It was a second defeat in a row, however, for the Irish province, who produced a much improved performance from that which saw them go down 41-5 at home to Bordeaux-Begles last week.

Saracens edged ahead early on when Argentine flanker Juan Martin Gonzalez rose highest to collect a clever probing kick by Owen Farrell, before shrugging off a number of challenges to rampage over the line, with Farrell unable to convert.

Soon after, Ireland international Bundee Aki responded for Connacht, the centre barging over from close range after a lineout provided the platform for the score.

Jack Carty set up the set-piece with an excellent kick into the corner and subsequently added the extras to make it 7-5.

Farrell replied with a penalty but Connacht's second try was not long in coming, scrum-half Caolin Blade spotting a gap at the side of the ruck and darting through to stretch over the line and dot down. Carty split the posts for the additional two points.

The visiting number 10 was again accurate from the tee when Farrell was deemed to have overreacted to a hard shot by Shayne Bolton and a penalty was awarded.

The hosts reduced their deficit to four points when they drove towards their opponents' line with a maul, with George steering from the back and then rumbling over the line.

Farrell was off target with the conversion but made amends a few minutes later with a successful penalty attempt.

A Saracens lineout again set up their third score, the resulting maul seeing George go over again after a powerful shove. Farrell again skewed his conversion wide.

Mark McCall's side secured a bonus point with their fourth try soon after the restart as a clever kick through by Alex Goode was gathered by Hartley, who ran in under the posts to score on his Champions Cup debut.

Sarries continued to dominate possession and territory and were rewarded for their supremacy when Farrell kicked a further penalty. Farrell then provided a superb pass for wing Sean Maitland to gather and dive over in the corner after a sweeping move from one side of the pitch to the other.

With Cian Prendergast in the sin-bin for going off his feet, Farrell's penalty extended the advantage to 21 points.

Within minutes it was the turn of Saracens right wing Lucio Cinti Luna to cross in the opposite corner to Maitland, stepping inside John Porch and running in try number five for his side.

Home second row Maro Itoje was then yellow-carded for a high tackle and Connacht replied with a third try of their own, replacement JJ Hanrahan finding a gap and skipping over after good build-up play culminated in a skilful offload from Aki.

The try-scoring action continued as Hartley scored his second, providing the finish after collecting another clever kick.

Joe Joyce then surged over to clinch a bonus point for Connacht and a breathless second half continued when Theo Dan got his name on the scoresheet with an eighth Saracens try.

The replacement hooker used his team's tried and tested maul as his launchpad to surge over, but the scoring was not yet finished as Prendergast grabbed a late consolation try.

Saracens: Goode; Cinti Luna, Tompkins, Hartley, Maitland; Farrell, Davies; M Vunipola, George, Clarey, Itoje, McFarland, Gonzalez, Christie, B Vunipola.

Replacements: Dan, West, Mulipola, Tizard, Knight, Van Zyl, Parton, Lewington.

Connacht: Porch; Ralston, Farrell, Aki, Bolton; Carty, Blade; Duggan, Heffernan, Aungier, D Murray, Thornbury, Prendergast, Oliver, Boyle.

Replacements: Tierney-Martin, Buckley, Bealham, Joyce, Butler, McDonald, Hanrahan, Kilgallen.

Referee: Luc Ramos (FFR)