A move for Chelsea's David Luiz is among the deals Arsenal are working on as they bid to sign a centre-back.
Luiz did not take part in first-team training with Chelsea on Wednesday. He was present at their Cobham base and did not refuse to do anything - but was not involved with the main group.
Blues boss Frank Lampard will comment on the situation at Friday's news conference to preview Sunday's Premier League opener at Manchester United.
Luiz, 32, is under contract until 2021.