Gloucester closed the gap at the top of Pool Six to just four points after despatching a brave Calvisano 48-5 at Kingsholm on Saturday.
The hosts took a long time to subdue their battling hosts but in the end got the job done with splendid long-range tries from Matthew Watkins and Lesley Vainikolo.
With Cardiff Blues winning in Biarritz earlier in the day, Gloucester knew anything less than a bonus-point win over the Italian strugglers would all but put an end to their chances of progressing to the knock-out stages.
They took a third minute lead when Ryan Lamb marked a stray Calvisano kick in his own 22 and set off immediately.
The visitors were penalised but Gloucester elected to kick that goal via Lamb, who converted another two minutes later.
After a line-out, Gloucester's Italian lock Marco Bortolami was warned by the referee for scuffling with his compatriots. And for the next 20 minutes, Gloucester struggled to get any continuity in their game.
Some stout Italian defence regularly thwarted the home side who were making careless unforced errors in their frustration at not being able to break the opposition line.
It got worse for the home side when, in attempting to clear his lines, Lamb had his kick charged down by opposite number Gerard Fraser, who followed up for the shock score.
The outside-half failed with the difficult kick to give his side the lead.
Gloucester finally constructed their opening try on the half-hour. From a scrum 22 metres out from the Calvisano line, Lamb, Mike Tindall and Olly Morgan executed perfectly a pre-planned move which saw the full-back put Mark Foster over in the corner for a splendid score. Lamb converted from the touchline with an excellent kick.
Following that score, Gloucester began to play with far more purpose and continuity with the Italian defence now struggling to cope.
And, in first-half overtime, Gloucester deservedly got their second try when a clever pass from Lamb sent Luke Narraway in under the posts. Lamb converted to give his side a 20-5 interval lead.
A 55-metre run from the impressive Olly Morgan immediately put Gloucester back on the attack in the second half and they should have quickly extended their lead.
But Apo Satala, in the process of scoring, lost the ball over the visitors' line and, minutes later, they threw away another chance when, but for a poor pass from Morgan, Vainikolo would have scored.
However, the Tongan-born England wing soon made amends by breaking away from a ruck to score a solo try which Lamb converted.
All Black prop Greg Somerville was introduced to make his Gloucester debut after 50 minutes, replacing the injured Alasdair Dickinson.
Olly Barkley was also introduced as Gloucester sought that vital fourth try - and it came after 63 minutes when Watkins raced in from half-way but that effort was bettered when Vainikolo intercepted and ran 80 metres for the try.
Watkins then ran in another long range effort with Lamb converting all three late efforts to give him a 100 per cent strike rate.
Tries: Foster, Narraway, Vainikolo 2, Watkins 2
Con: Lamb 6
Pen: Lamb 2
Gloucester: 15 Olly Morgan, 14 Mark Foster, 13 Mike Tindall (c), 12 Matthew Watkins, 11 Lesley Vainikolo, 10 Ryan Lamb, 9 Gareth Cooper,
8 Luke Narraway, 7 Apo Satala, 6 Peter Buxton, 5 Marco Bortolami, 4 Adam Eustace, 3 Carlos Nieto, 2 Andy Titterrell, 1 Alasdair Dickinson.
Replacements: 16 Scott Lawson, 17 Dave Young, 18 Greg Somerville, 19 Will James, 20 Rory Lawson, 21 Willie Walker, 22 Olly Barkley.
Calvisano: 15 Ben Smith, 14 Daniele Forcucci, 13 Gonzalo Gonzalo, 12 Matteo Pratichetti, 11 Andrea Pratichetti, 10 Gerard John Fraser, 9 Paul Griffen, 8 Alessandro Zanni, 7 Aaron Persico, 6 David Dal Maso, 5 Cameron Treloar, 4 Justin Purll, 3 Alejandro Moreno, 2 Leonardo Ghiraldini, 1 Gabriel Bocca.
Replacements: 16 Ben Evans, 17 Tommaso D'Apice, 18 Peter Sidoli, 19 Filippo Cristiano, 20 Pino Patelli, 21 Nanni Raineri, 22 Luke McLean.
Referee: Tim Hayes (Wales)