Castres had won their last 13 matches at Stade Pierre Antoine and it seemed that stretching that to 14 was not going to happen as the Warriors held the lead until the dying seconds.

Glasgow’s cause was not helped when lock Tom Ryder was yellow carded in the 65th minute following a line-out – and that concern was doubled when replacement wing Byron McGuigan joined him in the sin bin minutes later.

And while down to 13 men Castres cashed in with a powerful driving maul in which flanker Yannick Caballero was driven over by his fellow forwards.

Daniel Kirkpatrick converted to put Castres ahead for the first time with just five minutes remaining – Ruaridh Jackson then seeing his potential match winning penalty bounce back off the right post and let the home side off the hook.

But indiscipline ultimately cost the Warriors as they had to settle for just a losing bonus point while Castres moved up to second place in the group just three points adrift of Ulster Rugby.

However, in the wake of their 9-6 home defeat by the French club in Round 3 head coach Townsend had demanded “it is all about providing a response to our defeat last Friday which was our poorest display – certainly in terms of accuracy – of my time at Glasgow.”

They did that – and more – with the 39 minutes wait for a try worth every second.

The Warriors’ line-out was functioning superbly, with prop Gordon Reid a key player, and it provided the half chance for No 8 Ryan Wilson to slice through the home defence.

His gallop towards the line was always going to be contained but he found his back row colleague John Barclay up on his shoulder in support.

The flanker went over with two Castres players clinging on but it came at the cost of Barclay suffering a hamstring injury and departing in some agony.

The first five minutes produced successful penalty goals for Peter Horne and Romain Teulet but much of the half was an arm wrestle in the French sunshine.

Fijian scrum half Niko Matawaku produced a glorious solo effort from a quickly taken penalty, only to be hauled down inches short of the Castres line, and then pulled off a potential try saving tackle from a rare threat by the home side.