The Saints confirmed less than an hour before kick-off in Paris that the 22-year-old was ill and would not be wearing the No10 shirt at Stade Jean Bouin.
.Bristol boss Pat Lam believes his Gallagher Premiership leaders should be unbeaten after the first block of six league games.
Bristol regained top spot in the Gallagher Premiership as centre Kalaveti Ravouvou scored two tries to underpin a 31-23 victory over champions Northampton at Ashton Gate.
Round six of the Gallagher Premiership promises to deliver another thrilling weekend of action, with teams looking to solidify their positions ahead of a break before the Test rugby returns in November.
Northampton Saints have handed a debut to England U20 international George Makepeace-Cubitt, who was playing in National League One last season for Rams Rugby.
Coventry taught England U20s a valuable lesson as the club marked their 150th anniversary in style at Butts Park Arena.
Northampton Saints announced the immediate signing of fly-halves Charlie Savala and George Makepeace-Cubitt.
The Irish closed out a hard-fought five-try, 36-0 win over Scotland in Cork, their last three tries coming in the closing 10 minutes, and it left England needing to beat world champions France in Pau to take the glory.