France squad member Arthur Retiere scored three tries as La Rochelle trounced Castres 62-3 in the French Top 14 on Saturday.
The visitors played their first fixture in almost a month after registering more than 11 coronavirus cases over the past four weeks.
Coach Mauricio Reggiardo made six changes from the loss to Stade Francais on September 13.
The illness outbreak at the club had caused them to forfeit a Challenge Cup quarter-final and postpone two domestic fixtures.
"It would be too easy to say it's the fault of Covid-19 or the lack of competitive matches. We have no excuses," former Argentina prop Reggiardo said.
"La Rochelle put us under pressure and were better than us," he added.
At Stade Marcel Deflandre, the hosts led 15-3 after 20 minutes as Jules Plisson kicked five penalties and Benjamin Urdapilleta claimed his side's only points.
The floodgates opened four minutes later as hooker Pierre Bourgarit crossed for the first of his two tries.
At the break, the home side had a 41-3 advantage after winger Retiere, named in les Bleus squad to prepare for next Saturday's Test match with Wales, scored twice.
They were awarded a penalty try after 63 minutes and South Africa winger Dillyn Leyds dived over two minutes later to cross the half-century of points.
Retiere, 23, completed his second hat-trick of the year in the closing moments as his outfit moved up to second in the table.
Reggiardo's men drop to 13th spot with just one victory so far this term.
Elsewhere, Springboks' Rugby World Cup winner Cheslin Kolbe scored his seventh try in as many matches this season in Toulouse's 36-16 win at Brive.
On Sunday, Lyon host Bayonne and Clermont welcome Stade Francais.