Arsenal are still waiting to discover the full extent of Martin Ødegaard’s ankle injury but their captain is expected to be unavailable for at least three weeks. This means he will miss Sunday’s north London derby and the trip to Manchester City on 22 September.

Ødegaard left the pitch in tears after a challenge from Christoph Baumgartner during Norway’s win over Austria on Monday and was pictured on crutches on Tuesday when he returned to Arsenal for more tests, with the Norwegian FA stating he had sustained “a bad ankle injury”. The 25-year-old is understood to have had a scan and will be assessed further by Arsenal’s medical staff as the bruising subsides.

Related: Nations League roundup: Norway’s Martin Ødegaard forced off with injury

But while Norway’s team doctor, Ola Sand, revealed that the initial MRI scan had ­indicated no fracture, he is still likely to be sidelined for at least the rest of September and would miss Arsenal’s opening Champions League game against Atalanta and the visit to City three days later.

“Such ankle injuries often take at least three weeks,” Sand told the Norwegian newspaper VG. “What we have so far obtained from the MRI examination in London is that there is probably no fracture in the ankle. It is always a bit difficult to interpret an MRI scan when you have had an old injury, but Arsenal are almost certain there is no breach, but this may still take some time.”

Ødegaard’s absence means Mikel Arteta will be without three key midfielders for the meeting with Tottenham. The new signing Mikel Merino is out for two months because of a shoulder fracture and Declan Rice is suspended after his red card against Brighton.

Jorginho – who signed a contract extension in May but has yet to feature this season – is expected to start alongside Thomas Partey, while Arteta also could opt to move the defenders Jurriën Timber, Oleksandr Zinchenko or the striker Kai Havertz into midfield. The summer signing Riccardo Calafiori had to return early from international duty with Italy after colliding with France’s Ousmane Dembélé but is likely to be in contention against Spurs.

Arsenal will not be permitted to wear their home kit in the match for the first time since 1986 after Professional Game Match Officials Ltd ruled that it featured “too much white”. They will instead wear their black away kit with Tottenham also ­wearing different colours for the return fixture in February.

Meanwhile, the Premier League’s independent key match incidents panel has unanimously supported Chris Kavanagh’s decision to send off Rice against Brighton. The England midfielder was shown a second yellow card for delaying the restart of play.