Cardiff Blues romped to their biggest Heineken Cup victory when they beat Rugby Calvisano 56-20 at Centro Sportivo San Michele in Round 1 - but now the acid test comes with their Millennium Stadium showdown with Gloucester Rugby on Sunday.

The 56 points scored against the Italian champions surpassed the 48 scored against reigning Heineken Cup champions Munster by Cardiff RFC way back in 1996, but international flanker Martyn Williams insists feet will remain firmly on the ground in the build-up to the big Anglo-Welsh clash.

"[Gloucester] will be the time to judge what we can do in Europe and when we will find out where we really stand," said Williams. "At the moment we are still finding our feet but it will be our hardest game of the season so far and only then we will know what level we are playing at.

"Any tries and bonus points are very important in this competition. If you pick them up along the way it could make the difference when it all goes into the mix at the end of the group stage.

"And while we are still under no illusions about how tough a group this is we really could not have asked for a much better start although at the end of the day the result in Calvisano is nothing more than a confidence boost and we know we have to go up a few levels to compete with Gloucester, one of the best sides in England.

"As you look at the [Gloucester] team sheet, it's very hard to find a weakness. But to play at the Millennium Stadium against a team with so many household names will be a fantastic occasion.

"It's going to be massive and that's the great thing about Europe. Yes, it will be a tough game for us but, if we concentrate on our own game and give our all, hopefully that will be enough.

"We are nowhere near our peak yet. We have shown glimpses and hopefully that is all building up to a really big performance.

"There's definitely still a lot more to come from us. You should never be satisfied with a performance and you always have to be looking to improve.

"Sunday will be a really big step up for us, something entirely different to Calvisano. But it's brilliant and that's the kind of game you want to be involved in.

"The big test will be in defence as Gloucester have so many attacking weapons that we really have to step up in that area.

"That said, it was a good result and, first and foremost, it was important for us to get a win out there so to score that many tries was just a huge bonus.

"It took us a while to grind them down. But we played some good stuff in the second half and it was just too much for them.

"It was a no-win situation because everyone expects you to get a result but the manner in which we did it was very pleasing.

"It was tough in the first half, especially being down to 14 men for 20 minutes of it. We held out though and then the boys showed how skillful we can be when the game opened up.

"There is still a lot for us to work on and we won't be resting on our laurels. But we have to be happy with that score.

Tickets are still on general sale, call 029 2030 2030 or buy from Ticket marquee outside Millennium Stadium Gate 3 on Sunday.