The Waratahs' play-off hopes all but evaporated in a 23-15 loss to Argentina's red-hot Jaguares at Bankwest Stadium on Saturday night.

A try-scoring double from Pumas winger Ramiro Moyano did the damage as the Waratahs slumped to their eighth defeat of the season.

All eight losses have been by eight points or less and skipper Michael Hooper was unable to hide his exasperation.

"It's like every game this year, you look up, 70 minutes and the game's in the balance again. We just haven't been able to grab the game and run away with it," Hooper said.

With just three rounds remaining, the Waratahs now trail the Brumbies by eight points and Melbourne Rebels by seven in the race for Australian conference honours and a guaranteed finals berth.

Even if they beat the Rebels on Friday night in Melbourne, then the Brumbies in Sydney in the penultimate round, the Tahs would need an improbable slip-up from the Brumbies against the bottom-placed Sunwolves next week to have any faint hope of making the play-offs.

"It's going to be very difficult from here on in," Gibson said.

"In terms off those three games, we're very much still wanting to play the rugby that we've set out to play all year. That hasn't changed for us.

"I know guys will turn up and keep fighting, keep answering the bell, and that's what I expect.

"We've got a lot of pride in or team and a lot of pride in our jersey, so there's plenty to play for."

On their latest lacklustre display, the Waratahs would only be making up the numbers in the finals anyway.

While once again gritty against the Jaguares, who have rocketed to second on the ladder with seven wins from their past eight starts, Gibson's side lack the firepower and polish to seriously contend for silverware in 2019.

As if having try-scoring whiz Israel Folau's contract terminated last week wasn't enough, the Waratahs will also be without fellow dual international Karmichael Hunt for the rest of their campaign.

The Wallabies World Cup hopeful last less than two minutes on Saturday night before succumbing to a knee injury.

"Karmichael looks like he's got a grade three medial strain, so that's definitely season ending," Gibson said.

The Waratahs have now lost both their matches at Bankwest Stadium by an identical scoreline but in ironically contrasting fashion.

When they lost 23-15 to the Sharks three weeks ago, Bernard Foley's unsuccessful conversion attempt from in front after the bell denied the Waratahs a precious bonus point.

This time, they conceded a penalty goal after fulltime to miss out on a consolation competition point.

Australian Associated Press