Midfielder Ismaila Soro and winger Mikey Johnston both suffered suspected hamstring strains, while forward Karamoko Dembele also limped off. Goalkeeper Vasilis Barkas pulled up in the pre-match warm-up to add to Postecoglou’s concerns ahead of facing Danish side Midtjylland at Celtic Park next Tuesday.
“It’s a fine line for us,” said Postecoglou. “We are trying to get as much work into the boys as possible without compromising their wellbeing. We have picked up a couple of injuries tonight, which is disappointing.
“We are not great on numbers at the moment, so it’s disappointing that we may have lost a couple tonight. But we will see how it all washes up and hopefully it’s not too bad.”
Postecoglou did add to his squad earlier in the day when Celtic completed the £3.5 million signing of 19-year-old Israeli winger Liel Abada from Maccabi Peta Tikvah on a five-year contract.
"I'm really pleased to get him in,” Postecoglou told Celtic TV. “He's a young lad who has shown real promise.
"I'm very keen on bolstering our attacking third and our players there, the kind of players who can play our football. He's exciting and he can score goals from wide areas. He's still young and still developing, so I'm pleased to get him in."
Aside from the injuries his squad picked up, Postecoglou was encouraged by Celtic’s performance against Bristol City which followed up previous friendly wins over Sheffield Wednesday and Charlton.
“It was a tough workout for the boys,” he said. “We had a really solid session yesterday as well. But to be fair, we started well and the first 45 or 55 minutes we were really good.
“We dominated the game, we played in their half, we created chances and didn’t really allow them much. So, again, there were some really positive signs.
“Overall, in terms of the football, it was another positive step. We want to dominate the game, we want to be the team that makes the other team adjust. For the most part, we were really good at that.”