The 29-year-old was given a four-to-six-week recovery timeframe, but an update provided by Gatland on Tuesday revealed that Ta'avao's issue is actually a suspected quadricep tear.
"We thought it was a knee contusion and a haematoma from the Blues game, and it's actually ended up being quite a significant tear in his quad," Gatland told reporters in Hamilton.
Gatland said that Ta'avao would see a specialist to assess whether an operation or rehabilitation is necessary, and that he could be sidelined for between eight to 12 weeks.
Jacobson, meanwhile, was pulled from the field inside the opening 10 minutes of the Brumbies clash in what was his first match back from a concussion problem which ruled him out of the All Blacks' World Cup campaign last year.
He was expected to be available for the Chiefs' match against the Sunwolves in Tokyo a fortnight ago, but a tight hamstring prevented him from travelling with the squad to Japan.
It was that hamstring issue which ultimately limited the 22-year-old's comeback appearance at FMG Stadium Waikato, as he watched the rest of the match from the team bench with an ice pack wrapped to the back of his leg.
Gatland described Jacobson's injury as a "neural" issue, and the two-test All Black would, at the minimum, miss the Chiefs' next fixture against the Waratahs in Wollongong next Friday.
However, the former Wales and British and Irish Lions boss conceded that it is likely that Jacobson won't play for the next couple weeks following that encounter.
"We thought he was 100 per cent and ready to go, from a running perspective he was good, but when you go out there, and it's a full-on game, pushing in the scrums and mauling and stuff, it's kind of a load that's hard to replicate from a training perspective," Gatland said.
"So we've just got to make sure that we do enough work on loading that up before he comes back."
Gatland is eyeing a return for Jacobson via the Chiefs Development side, who are scheduled to take on the Blues Development squad in Hamilton on March 13 ahead of the Chiefs' two-match tour of South Africa.
On a more positive note, 26-test All Blacks prop Nepo Laulala is a possibility to return to training next week after missing the last three rounds with a medial ligament injury in his knee which he picked up against the Blues.
Laulala's recovery timeframe was initially scheduled for up to six weeks, but a comeback on the training park could indicate his availability for the Waratahs clash.
This story originally appeared on RugbyPass and was re-published with permission.
