The French club currently head the group on 18 points, but Worcester and Dragons are only three points behind, and the Welsh region entertain bottom-placed Enisei-STM at the same time.

“The way the Pool 1 table looks, it seems that it will be the game that will decide who goes through to the quarter-finals,” said the South African.

“I would imagine that Dragons will get five points out of their game against Enisei. We will have a tough game against Castres.

“We will wait and see what side Castres bring, but we know from playing them over there that they are a good team.”

Solomons is happy that Worcester are at home, as they have won all their ties at Sixways Stadium so far in what he regards as a mixed Challenge Cup campaign.

“It’s been good in patches,” he commented. “We have played well at times and not so well at other times.

“Neither of our away performances against Castres and Dragons have been up to the mark. We would have liked to have performed better in those games, but we have performed reasonably well at home.”

That includes a 66-10 win over Enisei-STM in Round 5 last weekend, of which Solomons said: “The boys did really well. We scored some good tries and it was good to see so many youngsters out there.”

For Round 6, the Warriors chief recalls Scottish international Duncan Weir at fly-half and Perry Humphreys on the right wing after injury, while Cornell du Preez, who has been selected by Scotland for the Six Nations Championship, is also back at No.8.

Worcester Warriors director of rugby Alan Solomons believes that his club’s home game with Castres Olympique on Friday night will determine the quarter-finalists from Pool 1 of the European Rugby Challenge Cup.