Andy Friend has warned his players they could lose by "60 or 70" points against Ulster next week if they don't properly address their defeat to Glasgow.
Friend's side were second best throughout in their 42-20 defeat to the Warriors, whose sixth win from nine sees them solidify their place in the top four of the United Rugby Championship table.
For Connacht, a fifth defeat in the URC sees them lose further ground on their Irish Shield rivals in the race for Champions Cup rugby.
While Connacht briefly drew level at 17-17 and 20-20 early in the second half, three more Glasgow tries followed to kill the game off.
The Australian coach did not hold back his frustrations at the performance, describing it as "unacceptable".
"What was disappointing was the lack of energy and the lack of spark and stupidity of some of the penalties we gave away, we kept giving them access," he said,
"Areas that gave functioned well for us before didn't function. There are no excuses, that was unacceptable, that performance."
Despite big wins against Ulster, Munster and the Bulls this season, Saturday's defeat is a second at the Sportsground this season, following a similarly poor showing against the Dragons in October.
However, Friend (below) says the Glasgow loss was their worst of the campaign.
"We all felt in the team really flat after the Dragons performance, this one supersedes it," he said.
"We were worse today, and I hurt saying that. I wear that, I'm the head coach at the end of the day. I've to look at what got us to that state where I thought we were ready to go but we weren't.
"To have a reasonably packed house there, Tiernan O'Halloran's 200th game, Cathal Forde's first game, Gareth our physio's last game. It's pretty disappointing."
Connacht were without several first-team regulars due to Ireland's Six Nations preparations, and Friend rejected any suggestion that their depleted numbers were an excuse for the performance.
"I actually don't think there are mitigating circumstances," he said. "I keep saying we want to be a team that's got depth. We gave opportunities today, I thought we were right, but on that performance we weren't.
"Credit to Glasgow they were way, way, way better that we were today.
"We say we want to be the team that wants to be competing for silverware. Teams who compete for silverware have depth and when players get opportunities, they take it.
"There are other teams who are missing players at the moment as well, so I don't want us to be looking at that as an excuse. It can't be an excuse. If we're going to continue to grow as a province, we can't use it as an excuse. We can't be the honourable losers."
It leaves Connacht bordering on must-win territory for their rearranged game against Ulster on Friday, with a six-day turnaround for the trip to Belfast.
And Friend said there needs to be a serious improvement if they're to do the double on Dan McFarland's side.
"We've just made it harder for ourselves," he said.
"If we play like that, they'll put 60 or 70 on us."
