Leicester enhanced their chances of reaching the quarter-finals with a famous win thanks to a rare Brad Thorn try and 20 points from the boot of Owen Williams, while Drew Mitchell and Bryan Habana crossed the line for the visitors.
Castrogiovanni made 149 appearances and won four Premiership titles during eight years with Leicester, but was upset with the way the club handled his departure to the French Top 14 side amid suggestions he principally left to cash in on a pay rise.
“I thought f****** Leicester were f****** amateur,” he raged. “He [Cockerill] was saying that people go for money but he has a lot of f****** squad players who get paid as well. I paid my own f****** money to leave this club.
“I never want to speak with Cockers anymore. I am the kind of guy that If I hate you, if you are not clear with me or if you have been a ****, I never want to speak to you anymore.”
Harlequins boss Conor O’Shea, meanwhile, is adamant Nick Easter retains the ability to represent England after the veteran back-row forward carried the fight to three-time champions Leinster during their 24-18 victory at the Stoop.
No8 Easter powered over for the opening try after the scores were locked at 9-9 at the break, while Asaeli Tikoirotuma also touched down as unbeaten Quins moved three points clear of the Pro 12 side in Pool Two.
“I’ve always said he can still play for England because he can cover a few positions and is an old head,” said O’Shea. “Sometimes when you’re in those sorts of games you need those old people around.”
Wasps secured a bonus-point 32-17 victory at French Top 14 basement outfit Castres to maintain their hopes of making the quarter-finals.
Full-back Rob Miller, No8 Nathan Hughes and wing Sailosi Tagicakibau all scored tries as a penalty score and 12 points from the boot of Andy Goode saw third-placed Wasps close the gap on Leinster to three points.
London Welsh’s search for a first win of the season continues following a 25-13 reverse at the hands of Edinburgh at Murrayfield in the European Challenge Cup. The hosts instigated a comeback after wing Rhys Crane touched for the Exiles with an intercept try.