Arsene Wenger says Jack Wilshere has suffered no setbacks in his return from injury but cannot guarantee he will return to training in the next three months.
Wilshere, 20, has been out of action since sustaining an ankle injury in an Emirates Cup clash with New York Red Bulls in July 2011, with his return hindered by a setback suffered in January this year.
Wenger stressed that Wilshere's comeback remains on course, but it remains to be seen how much of the new campaign he will miss.
"It is impossible to set a concrete deadline at the moment, but it is all okay," he told Arsenal Player. "He is as quick as we expected him to be. His ankle is good and his knee is good. There is no setback. It difficult to say 'it will be this week in September or October' when he is back in training. He has been out for a year and I don't want to put any pressure on him."
Wenger said Emmanuel Frimpong, who damaged his knee while on loan at Wolves earlier this year, would return at "the end of September or perhaps into October", while fellow midfielder Tomas Rosicky, who sustained an injury while representing Czech Republic this summer, will also miss the start of the season.
"It will be six to eight weeks until he is back in training," Wenger said. "It was his [plantaris tendon]. It was done at the Euros."
Right-back Bacary Sagna, who sustained a broken fibula against Norwich towards the end of the season, is likely to be back next month. "He is doing very well," he said. "There are no problems there, but it will be the end of August for him."
Wenger confirmed that Mikel Arteta, Abou Diaby and Lukasz Fabianski are all now fit and available.
The Gunners boss was speaking following the announcement of the 24-man squad for the tour of Asia. Robin van Persie's exclusion had made headlines ahead of the confirmation on Saturday morning, but Wenger says he, along with several other Euro 2012 stars, is simply short of fitness.
"Some of them [will not go on tour] because they are too far behind to be competitive, but most of them will go," he said. "The German players [Podolski and Mertesacker] are just back in training on Saturday so they will be late. Some players have to work on their fitness so are a bit behind, like Van Persie, like Koscielny, like Giroud, who came in later. They are not ready to play games.
"Some players like Walcott and Oxlade-Chamberlain, they travel. Song, Diaby, Vermaelen, Santos, Gibbs, Szczesny, they will all travel. So will Gervinho - we have a very strong team out there. Rosicky is injured. Apart from that I think everybody travels.
"It is a first-team squad with a few young players who have a chance to play next season. You will see when we play the games that we will have a team out there who can play in the big games and have big experience of that."