The Blues outscored their Aviva Premiership hosts two tries to one at Sixways in the first of two summer fixtures prior to their RaboDirect PRO12 opener at Glasgow on September 6.
Flanker Macauley Cook and centre Richard Smith crossed for the visitors, with Rhys Patchell adding a conversion and a penalty and Gareth Davies slotting two three-point efforts in the first-half.
Worcester actually led 14-11 at the break but the Blues were good value for a win which would have been far more comfortable had Patchell not missed four of six attempts from the tee.
Davies blooded a number of young players for the first outing of his second season in charge and the former Wales international was delighted with the attitude and the application shown by his entire squad.
“The boys showed great physical and mental strength,” said Davies, whose previous post before joining the Blues was as an assistant coach at Worcester.
“It was great to win, but for the young players to play the way they did really pleased me. I thought we played well: we’ve worked very hard over the pre-season and the players have been excellent.
“We squandered a couple of opportunities but we looked a lot more solid in all aspects. I’m far happier than I was at this time last year.
“The physicality and the work we’ve been doing in training came to the fore and we’ve now got a good platform to move forward to the next game.”
That next game is at home to Sale this Friday, with the Blues preparing for their first official outing on the new artificial pitch at Cardiff Arms Park.
And Rees, who led the Blues for the first time since his summer move from the Scarlets, is confident his new team will kick on against the Sharks in game two and as the season progresses.
“It’s still early days but it was nice to see some of the things we’ve put in place coming off against Worcester,” added Rees.
“It was a massive game. For us to go to Worcester and get a result speaks volumes. I thought we were quite comfortable in certain aspects of the game.
“There were a lot of positives and we’re looking forward to playing Sale Sharks at Cardiff Arms Park on Friday night.
“The Blues had a tough time last season but we can only get better. We have a strong squad this season. We’ve the experience of Gethin Jenkins returning and have the other boys from the Lions tour coming back in. Sam Warburton, Alex Cuthbert and Leigh Halfpenny will raise the bar again.”
