Bath made a winning return to the European top flight after a season's absence with a 23-0 victory over Italian side Benetton Treviso in Pool 5 of the Champions Cup.

The scoreline did not do justice to the Italians who monopolised possession for long periods but lacked a cutting edge behind their powerful forwards.

Flanker Zak Mercer scored a timely try that gave Bath a 13-0 lead at the break and Aled Brew added a second late on but they never looked like getting a bonus point. Having prop Nick Auterac and hooker Tom Dunn sin-binned did not help their cause.

Josh Lewis, the 25-year-old Welsh stonemason making his first start for Bath, put them 6-0 ahead in as many minutes with a pair of penalties but they could not press home the advantage as Benetton's pack began to take control, mainly through their superior scrum.

After the home pack conceded a penalty on halfway at the end of the first quarter, they found themselves under the cosh for a full 10 minutes.

First it took a try-saving tackle by Brew to deny No. 8 Robert Barbieri, up in support of a storming run by fellow back-row Sebastian Negri.

Then a succession of scrum penalties and resets resulted inevitably in a yellow card for Auterac. It took another last-gasp tackle, this time by Semesa Rokoduguni, to stop left wing Tommaso Benvenuti scoring in the left corner.

When fly-half Ian McKinley did finally attempt a penalty on 32 minutes, he sent the kick wide.

As the clock ticked down to half time, Bath suddenly produced some magic as Jonathan Joseph released Rokoduguni on a jinking run down the right. The supporting Chris Cook finger-tipped inside and Mercer galloped 25 metres to the line. Lewis converted for a 13-0 lead.

Benetton got their own offloading game going soon after the restart but a loose pass was pounced on by Lewis who hacked downfield, winning a penalty under the posts and kicking the goal himself. Now the scrum battle began to turn Bath's way, but Lewis had a drop-goal attempt charged down and Dunn went to the bin on the hour mark for an illegal charge at a maul, an offence picked up by assistant referee Nigel Owens.

Brew's try was a classic move off the top of a lineout in the 70th minute, with Francois Louw providing the link and Lewis converted.