Leicester moved temporarily top of Pool 3 on Saturday thanks to a fine 47-8 victory over Viadana at Welford Road.
Scott Hamilton was again the Italian side's nemesis as the Tigers kept their Heineken Cup aspirations alive and kicking.
But Tom Croft was carried off after 27 minutes with a knee injury that threatens his Six Nations hopes.
Full-back Hamilton scored a hat-trick when Leicester crushed the same opponents 46-11 in Italy last year, and his two strikes at Welford Road today included the fourth try which ensured a maximum five-point haul.
Having conceded a late losing bonus point to Clermont before Christmas, Tigers knew they needed a full-house win before facing Ospreys in Swansea next week.
And the visitors encouraged the home support to expect a rewarding afternoon when fly-half Pierre Hola sent the kick-off directly into touch.
The buzz became a mass intake of breath, however, when full-back Garry Law signalled going for goal - from 60 yards - in the third minute. His effort made the distance, but faded right of the posts.
When Leicester were awarded their first penalty minutes later, Toby Flood opted for touch, the lineout was won and, three phases later, Dan Hipkiss swept through two defenders for a sixth-minute opening try. Flood converted from wide on the right.
Law reduced the arrears in the ninth minute with a well-struck penalty, this one from a more modest 25 yards following an offside infringement by Hamilton.
Leicester were playing as if the outcome were a foregone conclusion, something Viadana were happy to challenge with a succession of strong tackles. And they knew that conceding penalties would not bring the customary barrage of points because Leicester were anxious to score at least four tries.
They grabbed their second on 20 minutes when Flood ran a penalty awarded for offside. Jordan Crane opened up the defence on the right with a clever grubber kick and Ben Woods punished a rather casual effort by Michele Sepe to ground the ball, pouncing from behind the wing to get the vital downward pressure. Flood's conversion was again spot-on from the right wing.
Leicester lost Croft in the 27th minute with an injury to his left knee that required two helpers to get the England flanker off the field. Craig Newby replaced him.
The third try arrived after 32 minutes and was sparked by a frankly frightening thundering charge at the Viadana defence by Alesana Tuilagi.
It needed so many defenders to halt the resultant drive on their line that when the ball came out to Flood, he dummied his own three-man overlap and scored by the posts, and completed the score by converting.
The job was completed two minutes later. Hamilton snaffled a loose ball and powered clear of the cover to score on the right and guarantee the essential bonus point. Flood made it four conversions out of four.
Viadana were now looking distinctly rattled and it was no surprise when they caved in again on the stroke of half-time, Hamilton racing onto a short inside pass from Flood to score his second try. Flood nailed his fifth conversion.
Things got worse for Viadana when Law was sin-binned in the 49th minute for persistent offending at rucks. But having withstood a siege comprising five consecutive penalties on their line, Viadana stunned the crowd by breaking out to snatch a try by scrum-half Pablo Canavosio after 55 minutes.
To their credit, Viadana used their bench and re-organised to the point where Leicester's expected avalanche of second-half tries failed to materialise. However, some clumsy passing and wasteful lack of concentration by Leicester were also factors.
When Leicester did score their sixth try, it came half an hour into a scrappy second half as Hipkiss recorded his second strike from close range after a pass from Sam Vesty.
That score burst the Viadana balloon, and a storming run by Tuilagi on 74 minutes ended with his clever outside pass arming Aaron Mauger to score on the left.
Tries: Hipkiss 2, Woods, Flood, Hamilton 2, Mauger
Cons: Flood 5, Vesty
Leicester: 15 Scott Hamilton, 14 Alesana Tuilagi, 13 Dan Hipkiss, 12 Sam Vesty, 11 Lote Tuqiri, 10 Toby Flood, 9 Ben Youngs, 8 Jordan Crane, 7 Ben Woods, 6 Tom Croft, 5 Geoff Parling, 4 Louis Deacon, 3 Dan Cole, 2 George Chuter, 1 Marcos Ayerza.
Replacements: 16 Mefin Davies, 17 Boris Stankovich, 18 Julian White, 19 Craig Newby, 20 Lewis Moody, 21 James Grindal, 22 Aaron Mauger, 23 Johne Murphy.
Viadana: 15 Garry Law, 14 Matteo Pratichetti, 13 Sam Cox, 12 Lloyd Johansson, 11 Michele Sepe, 10 Pierre Hola, 9 Pablo Canavosio, 8 Jaco Erasmus, 7 Andrea Benatti, 6 Aaron Persico, 5 Sean Hohneck, 4 Carlo del Fava, 3 Julio Garcia, 2 Luigi Ferraro, 1 Plinio Sciamanna.
Replacements: 16 Roberto Santamaria, 17 Luigi Milani, 18 Mattia Cagna, 19 Josh Furno, 20 Gareth Krause, 21 Mickey Wilson, 22 Aldo Birchall, 23 Samuele Pace.
Referee: James Jones (Wales)