Though his recovery is "going well", Christian Horner admits that Daniel Ricciardo is likely to miss the forthcoming races in Singapore and Japan.
The Australian suffered a fractured metacarpal when he crashed during practice for the Dutch Grand Prix at Zandvoort.
While it was never likely that he would recover in time for Monza a week later it was hoped that he would be back in time for Singapore.
However, speaking to the media at Monza, Red Bull boss, Christian Horner has admitted that the Australian is unlikely to be back behind the wheel until October.
"I think certainly Singapore, I don't think there's any chance he'll be ready for then," said the Briton. "It would be optimistic for Japan but his recovery is going well. He's got mobility of the hand and is into rehabilitation now.
"We've seen with motorcyclists rushing comebacks, they can sometimes do more damage," he added. "So we just want to make sure he's fully fit before we get back in the car."
Replacing the Australian at Zandvoort and again at Monza was New Zealander, Liam Lawson, who gave a good account of himself this weekend following his baptism of fire in Holland.
"I think he did a solid job today," said Horner. "I haven't followed his race that closely... they went for a two stop, which was unconventional on today's strategy. So, I'll have to have a look at the analysis after the race, but I think he's acquitted himself very well."
Currently second in the Super Formula series, Lawson has experience of Suzuka, which comes a week after Singapore.
"I should think he's pretty keen to be in the car in Suzuka," said Horner, "but we'll just take it on a day-by-day basis and see how the recovery and nature takes its course."
"More and more comfortable, but just a little bit disappointed with the race," said Lawson of his Monza race, which saw him finish just outside the points.
"We maybe had the pace for points, I'm not sure, we have to look into it," he added. "I had a bad start, and that's where we really lost the chance. I'm disappointed to be so close."
With teammate Yuki Tsunoda failing to make it to the start, AlphaTauri's hopes rested solely on the shoulders of the young kiwi, who admitted to feeling much more comfortable in the car this weekend.
"Much, much more prepared, to be honest, but unfortunately not enough to fight for points," he said. "It definitely helps with all the work we did leading up, and I feel much more comfortable with the car.
Asked about the biggest challenges, he was in no doubt. "Just procedures," he replied. "There's a lot to do behind the wheel of the car, and it's obviously better if you don't have to look down at what you're doing, and that's something that takes a little bit of time."