In atrocious conditions in the south west of France, Scarlets went down to a 34-16 defeat to Top14 high-flyers Castres Olympique in the opening round of the EPCR Challenge Cup.

Missing so many senior players through injury, it was always going to be a tough challenge for Dwayne Peel’s side against a super-confident French outfit who are currently flying in third spot in their league standings.

Despite a poor opening at the Stade Pierre-Fabre, the West Walians clung on to Castres coat-tails for the majority of the contest, but it was the home side's firepower up front, particularly at the set-piece, that proved crucial.

Fly-half Ioan Lloyd scored all of Scarlets' 16-points, including a second-half try, while there were impressive displays from young back-rowers Ben Williams and Teddy Leatherbarrow, but it was Castres who bagged the maximum haul from their five-try display.

It was a disastrous start for the Scarlets, who had Steff Evans yellow carded after just 90 seconds for a deliberate knock-on, even though there appeared to be obstruction on Jonathan Davies in the build-up.

It led to immediate pressure inside the Scarlets 22 and an early try from a line-out maul, scored by wing Josaia Raisuqe.

Scarlets managed to haul themselves into the contest as the half wore on and two penalties from the boot of the in-form Lloyd made it a one-point game after 16 minutes.

The West Walians had opportunities, through a Ben Williams bust and a Tom Rogers break, but the greasy conditions meant they were unable to maintain the fluidity of the previous week.

With Castres pressing for a second try, scrambling defence looked like it had halted the attack, but scrum-half Kieran Hardy was deemed to have infringed, was shown yellow and from the short-range line-out, scrum-half Jeremy Fernandez darted over.

French ill-discipline from the restart allowed Lloyd to bisect the uprights with a third penalty success, but there was still time for another Castres try before the break; No.8 and player of the match Abraham Papalil touching down from another line-out surge.

A rampaging run from the impressive Williams offered Scarlets hope of a response in the final move of the match, but Ryan Conbeer was forced into touch five metres out to leave the score 17-9 at the interval.

It was Castres who extended their advantage swiftly after the restart; full-back Julien Dumoran claiming the bonus-point score after Scarlets had been turned over on halfway.

With the home pack disrupting the Scarlets line-out, the visitors struggled to get a foothold in home territory, but did get a lifeline with a try on 50 minutes by Lloyd.

A thumping hit by Wales centre Johnny Williams on fly-half Louis de Brun saw the ball dislodged and the fly-half gratefully scooped up at the ball and raced unopposed to the posts. Lloyd added the extras.

However, that was as good as it got for the Welsh side.

Le Brun landed a penalty and then finished off a beautifully crafted try from a series of sublime offloads.

Scarlets battled to the end with Ioan Nicholas and Steff Evans almost going over, but Castres were deserved winners.

Attention now turns to the Friday's visit of Georgian side Black Lion, who were beaten at home 15-10 by Gloucester on their debut in the competition.

Castres - tries: J. Raisuqe, J. Fernandez, A. Papalili, J. Dumoran, L. de Brun. Cons: de Brun (3). Pen: de Brun.

Scarlets - Try: I. Lloyd. Con: Lloyd. Pens: Lloyd (3)

Scarlets: Tom Rogers; Steff Evans, Jonathan Davies, Johnny Williams (repl Ioan Nicholas 57), Ryan Conbeer, Ioan Lloyd (repl Charlie Tircombe 64), Kieran Hardy (repl Archie Hughes 57), Steff Thomas (repl Sam O’Connor 70), Ryan Elias (repl Shaun Evans 50), Joe Jones (repl Harri O’Connor 57), Morgan Jones (repl Ed Scragg 57), Jac Price, Ben Williams, Teddy Leatherbarrow, Carwyn Tuipulotu (repl Iwan Shenton 60).

Referee: Nika Amashukeli (Georgia)