Strong running second row Lionel Nallet led the way for the hosts, blasting his way over for two tries in a 28-9 win to ensure a victory against a Welsh side whcih never got out of first gear.
"It's very disappointing," admitted Rees. "We knew it was going to be a tough ask after the defeat France had against Italy. They dominated us up front and we came away second best.
"There were a lot of errors at the ruck areas. We gave them a lot of ball there.
"We lost the game in the first half as far as I'm concerned.
"We're disappointed to lose out tonight, but we have had three good wins. But we've only got ourselves to blame tonight. We got to make sure we learn from this."