Saracens coach Alan Gaffney has challenged his squad to improve quickly after today's 71-7 Heineken Cup win at home to Viadana - so that New Zealander Chris Jack can sparkle at Vicarage Road this season.

The 67-cap Kiwi lock made his competitive bow for Sarries during their 10-try romp against the Italian minnows, and Gaffney is convinced Jack has set the standard with his performance.

``I thought Chris Jack was outstanding,'' he said.

``Chris is very good on the ball, good in the air and just an excellent line-out jumper.

``We've got to raise our pace, because he's so good across the ground - and we're probably not good enough at the present time to help him.

``We need to improve and make sure we get the best out of him. His fitness is fine; he hasn't played a lot of rugby lately but he just kept going.''

Sarries number 10 Glen Jackson was once again the star of the show, scoring 25 points - including a second-half touchdown as Gaffney's men ran riot.

Sakiusa Matadigo added the first try for Sarries, while Haughton (2), Ratuvou and England international Richard Hill also touched down in an impressive first-half showing.

Calvin Howarth took advantage of a loose pass from England discard Andy Farrell to score Viadana's only points of the game, racing 80 yards and adding the extras.

Viadana second row Dion Waller was sin-binned after the break as Sarries continued to dominate. But further scores from Jackson, Haughton, Ratuvou, Census Johnston and a late penalty try for a collapsed scrum saw Sarries march on.

Gaffney has nonetheless warned his squad they must keep improving if they are to avoid a giant-killing in the return match in Italy.

``The intensity was a pleasing aspect of the game,'' he said.

``To be ahead at half-time and to come out and score five tries in the second half was probably the most pleasing aspect.

``We didn't expect to win by that much. Viadana will be a very different proposition at home, but we'll go over to Italy with our heads screwed on.

``I thought we played very well in difficult conditions but I think we could and should have scored more tries.

``To put over 10 tries is something we've been striving to do and to put two back-to-back halves together is a real bonus.''

Brent Russell was also a relieved man at the final whistle.

The South African full back made his Sarries debut, after spending three months on the sidelines injured with a broken collarbone.

``My injury has been frustrating,'' he said.

``I've been out for three months but still made it in time for the English winter. In the first two weeks here in training, I broke my collarbone - and it was just frustrating.

``I've got to know the club, the players and the supporters - so it wasn't all bad. It's just the matter of getting back into it.

``It was good just to be out there and be a part of the team in a game situation. I'm a little rusty, but it was a good game to get back into.''