Chelsea fans mocked their rivals at Manchester United last weekend by hacking into the Old Trafford club's phone system and changing its recorded message.
Manchester United fans were greeted with a "we are the champions" chant by Chelski supporters instead of a recorded message stating the club was closed for the weekend, the Daily Mirror reports.
The subtle satirical prank bears the hallmarks of a low-tech hack by workers at one of the firms supplying the service, rather than anything more technically sophisticated.
Chelsea completed their first Premiership and FA Cup double last Saturday, beating destitute and already relegated Portsmouth 1-0 at Wembley. A week earlier the Blues secured the Premiership, one point ahead of 2008-09 champions Manchester United, in emphatic style with a 8-0 win over Wigan at Stamford Bridge. ®