Munster eked out a bonus-point win to open their Champions Cup pool campaign but it took until the closing minutes to finally grind down a stubborn Treviso side at a wet and windy Thomond Park.

Tries from BJ Botha, man of the match CJ Stander and Duncan Casey had confirmed the home side's dominance of an Italian side that has not won a Pro12 win since midway through last season but it was hard going in terrible conditions as European rugby returned to Limerick for another season.

Yet it was not until the 75th minute that Munster finally unlocked a 14-man Treviso defence to secure the additional point with wing Simon Zebo finishing off a period of concerted pressure with a dive over the line.

Botha, celebrating a contract extension to the end of the season signed this week, had opened the scoring with a crash-over try, converted by Ian Keatley and the South African tighthead prop was over the tryline again four minutes later only for the TMO to rule out a second score as the ball left Botha's control before grounding.

A second try inside 10 minutes might have opened the floodgates but Treviso bucked up after that and when No.8 Braam Steyn blocked a Keatley kick from in front of his posts he followed up with a kick ahead to pounce on the ball for an unlikely try, Jayden Hayward's conversion levelling the scores at 7-7.

Munster had been forsaking points from the tee in search of more tries but once Treviso levelled, Keatley was pointed towards the posts and he sent over a penalty on 19 minutes to re-open a lead that would not be lost again.

The bonus point had been expected and seen as essential in a group also containing Stade Francais and Leicester, but it was easier said than done and Munster did not score again until the 48th minute, Keatley with another penalty to push his side into a 13-7 lead.

Three tries were still required and Stander led by example, the stand-in skipper getting over in the 55th, followed by sub hooker Casey, on for the injured Mike Sherry since the 28th minute, finishing off from a lineout maul in the 69th.

Keatley added the conversion and Munster regrouped for a final push, their task helped by the 74th minute sin-binning of Treviso replacement prop Matteo Muccignat, paying the price for an accumulation of penalties.

Munster laid siege to the Italians' line, wore down their defence and brought them out of position before Conor Murray changed gear for a series of pick and goes to switch directions and put in Zebo for the finishing touch.

Nothing Munster didn't deserve but hard-fought and they will need to raise their game heading to Stade next weekend.

MUNSTER: A Conway (L Amorosino, 78); K Earls, F Saili, D Hurley, S Zebo; I Keatley (R Scannell, 78), C Murray (T O'Leary, 78); D Kilcoyne (J Cronin, 49), M Sherry (D Casey, 28), BJ Botha (J Ryan, 72); D Ryan, M Chisholm (D Foley, 66); D O'Callaghan (R Copeland, 55), J O'Donoghue, CJ Stander - captain.

TREVISO: L McLean; L Nitoglia (C Smylie, 55), J Hayward, E Bacchin, T Iannone; J Ambrosini, E Gori; M Zanusso (M Muccignat, 71), O Gega (D Giazzon, h-t), R Harden (F Filippetto, 49); D Naudé (D Budd, 49), J Montauriol; F Minto, A Zanni – captain (M Barbini, 28), A Steyn.

Replacements not used: Andrea De Marchi, S Christie.

Referee: Matthew Carley (England).