The Vicarage Road club meet the French side on Saturday for a place in the Heineken Cup quarter-finals after claiming a maximum five-point haul against Group Four’s bottom team.
But it was an unconvincing display, with Saracens subjected to a tense finish as spirited Treviso poured forward in search of the winning score.
“We will have to play at 100% for 80 minutes to stand a chance against Biarritz. Biarritz is a very hard place to go,” Diamond said. “But this result has helped our confidence and we’re confident that when we go down there we will give it the best shot we can.”
Dan Scarbrough, Dan Harris, Kevin Yates and Mark Bartholomeusz touched down but the contest was far closer than expected. A man-of-the-match display from South African fly-half Marius Goosen, who finished with 22 points, gave Treviso hope of registering a shock victory.
Diamond said: “We were a bit itchy in the last five minutes but last weekend we defended superbly against Gloucester but didn’t win. Today we were more adventurous and that worked well but our defence let us down. I’m just glad to get all five points and set up next week.
“The lads played well in the first half and attacked well. But we can’t just rely on attacking, we have to play set-pieces and have a kicking game. We go from hot to cold which isn’t acceptable. We have to learn how to kill games off.”
: Bartholomeusz, Scarbrough, Castaignede, Harris, Johnston, Jackson, Dickens, Yates, Byrne, Broster, Chesney, Vyvyan, Randell, B. Russell, Skirving.
: Sorrell for Harris (64), Bailey for Johnston (64), Rauluni for Dickens (53), Liffchak for Yates (64), Seymour for Randell (72).
: Williams, D. Dallan, Legg, Barbin, Calanchini, Goosen, Picone, Sbaraglini, Tejeda, Mazino, A. Pavanello, Wentzel, Dal Maso, Orlando, Wium.
: Pizarro for D. Dallan (12), Troncon for Picone (40), Ongaro for Tejeda (40), E. Pavanello for A. Pavanello (63), Allori for Dal Maso (57), Palmer for Wium (40).
: Malcolm Chang-Leng (RFU).
* LONDON IRISH limped into the European Challenge Cup quarter-finals after a tough 19-11 win over Italian minnows Parma. They now need victory over Madejski Stadium visitors Pau next weekend for a home quarter-final tie.
Gloucester followed Irish into the last eight, but they also produced a patchy performance on their travels before defeating Bucuresti 27-13.
Northampton are also on the brink of a last-eight spot following their 45-8 demolition of Guinness Premiership and Pool One rivals Bristol at Franklin’s Gardens.
Worcester’s 44-8 win against Sixways visitors Catania means a similar bonus point achievement in Montpellier next Friday night will take them through as Pool Five top dogs.
Newcastle eased into the last eight with a comfortable 47-20 win over Border Reivers.