Since they beat Harlequins in October 2001, Castres have played 16 matches away to Premiership opposition without repeating that victory.
With only two wins from their opening seven games in the Top 14, the visitors looked like they were saving themselves for domestic battles as Leicester cut them to ribbons in the first half.
The back-row pairing of Valentino Mapapalangi and Sione Kalamafoni – both summer signings – revelled in the space they were afforded and combined well for May’s opener.
Pool Four (after two games)
3. Racing 92
Fellow Tongan Telusa Veainu’s step, swerve and ability to sniff a gap made him a persistent danger and a hat-trick was just reward for his performance.
That the hosts allowed Smith to do the same in a lax final quarter was less impressive and such lapses in concentration might prove more costly in the back-to-back meetings with Munster that come next in Pool Four.
Genge makes his England case
England coach Eddie Jones was in stands, and while May’s on-going scoring streak and George Ford’s authoritative showing at fly-half will have strengthened their autumn international claims, it was Ellis Genge who provided most food for thought.
The 22-year-old loosehead prop was a rampaging presence in the loose, making yards and shrugging off tacklers with a piston-like hand-off.
With Saracens’ Mako Vunipola and Harlequins’ Joe Marler also occupying his position, he has some considerable competition to displace.
But his intoxicating mix of enthusiasm and aggression might well be unveiled with fixtures against Argentina, Australia and Samoa coming up in November.
‘Four incredibly tough games to go’ – coach quotes
Leicester head coach Matt O’Connor: “To take six points out of those first two games is important and puts you in a really good place from where you can probably control your own destiny.
“There are still four incredibly tough games to go, and we will have to be really good to get results across those games, but it is a good place to be at the moment.
“We were really good around the fringes. We spoke a lot during the week about going forward, and if we went forward, we knew we could get them on the edges.”
On possible knocks for Genge and Toomua: “Fingers crossed, they are not too serious.”