Pontypridd and Llanelli both registered convincing wins over Edinburgh Academicals and Connacht Eagles respectively and with Cross Keys edging Moseley in a tight encounter, it was left to Aberavon to make it four from four.
The Wizards were the last Welsh side to kick-off, taking on Scottish side Gala on Saturday evening. In the end, the late start failed to hinder Simon King's side as the boot of Sam Davies guided them to a convincing 31-17 victory away from home.
Ospreys Academy man Davies, who was named IRB Junior Player of the Year last season, kicked 16 points and wing Aisea Natoga crossed twice as Aberavon never looked like relinquishing a 13-3 interval lead.
King, who fielded just two players over the age of 23 in the side who took on Gala, said: "We were very pleased with the result as ours was one of the toughest fixtures. Gala are towards the top of the Premiership in Scotland, they are well coached and were well up for it on Saturday.
"It's very important for the Welsh sides to be successful if we want to move forward in the competition. Four wins is not only a boost for the Welsh clubs but also for the system overall. It's great we've got some success early on and it's an indication the Premiership is in rude health.”
While the eventual score line might look comfortable, Aberavon were forced to show plenty of heart after four yellow cards hindered their momentum. Ieuan Davies, Richard Thomas, Chris John and Ashley Evans all spent time in the bin but after Natoga's first try and the boot of Davies had put Aberavon clear, they held on in the second half.
Within 10 minutes of the restart, Davies' third penalty and conversion of Natoga's second try stretched Aberavon's lead to 3-23 with Paul Smithson's score closing out the game.
King added: "The kick-off time didn't help and we had four yellow cards so we were up against it and down to 13 men at one stage. But we showed a lot of character to stick it out - we showed great maturity for a young team.
"There were some new faces and we only had two training sessions together so everyone involved deserves a great deal of credit. We won the right to be in the competition and you couldn't fault the attitude of the players. We'll look forward to a clash with Bristol now.”
Before Aberavon made it four wins from four, Pontypridd had also enjoyed a comfortable win in Scotland, proving too much for Edinburgh Academicals to handle. Dale McIntosh's side secured a 53-13 victory at Raeburn Place, wing Matthew Nuthall getting the scoring going within five minutes.
Gavin Dacey, on his 200th appearance for Pontypridd, and Jake Thomas were among the other scorers as the Sardis Road club warmed up for a crunch home clash with London Welsh.
At Parc y Scarlets, Llanelli secured an even more impressive result as they scored a remarkable 11 tries in a 76-14 demolition of Connacht Eagles. Principality Premiership player of the month for September Steffan Evans opened the scoring with left wing Aaron Warren scoring four tries of his own and replacement Dion Jones adding a late brace.
Cross Keys earned a 20-16 victory over Moseley and the Gwent side were buoyed by some impressive performances from their younger players.
"It was a tough, tight encounter. Moseley threw everything at us for the first 10 minutes but we scored two lovely tries and managed to hold on,” said Keys head coach Greg Woods.
"Our young boys are doing really well this season. Angus O'Brien had another good game at fly half, he made a great break for one of our tries and we can look forward to a trip to Ealing Trailfinders now.
"They're a similar side to Moseley but we won't be daunted by it. Anyone who works in the Principality Premiership knows it is improving every year and Saturday's results showed that.”
British & Irish Cup Round One results:
Llanelli 76-14 Connacht Eagles
Cross Keys 20-16 Moseley
Edinburgh Academicals 13-53 Pontypridd
Gala 17-31 Aberavon
British & Irish Cup Round Two fixtures (Saturday, October 19):
Pontypridd v London Welsh (KO 2.30pm)
Aberavon v Bristol Rugby (KO 2.30pm)
Ealing Trailfinders v Cross Keys (KO 3.00pm)
Bedford Blues v Llanelli (KO 3.00pm)