Latham joined Worcester in the close season
Former Wallaby full-back Chris Latham opened his Worcester account with three tries in their nine-try 55-6 win over Petrarca in the European Challenge Cup.
Two tries each for stand-in skipper Latham and centre Alex Grove helped Warriors to a 38-6 half-time lead.
Wing Charlie Fellows and centre Sam Tuitupou also crossed - and it was much the same story after the interval.
Wing Rico Gear added another, before Latham completed his treble and Kiwi lock Greg Rawlinson finished the rout.
London Irish were also big winners, thumping Rovigo 78-3 - their biggest margin of victory and their highest-ever score in a European fixture.
Elvis Seveali'i scored twice for London Irish, as did replacement Peter Richards while Sailosi Tagicakibau, Seilala Mapusua, Paul Hodgson, Delon Armitage, Topsy Ojo and Shane Geraghty added the other tries - with Rovigo also conceding a penalty try after 32 minutes.
Former New South Wales Warratahs full-back Peter Hewat kicked eight conversions, with Armitage also adding an extra two points.
Newcastle also made a winning start, defeating Spanish side Cetransa El Salvador 63-0.