Manager Mikel Arteta claims Arsenal are in survival mode after he lost another two defenders to injury before overseeing a nervous 2-1 win against Brighton to move back to the top of the Premier League.Jurrien Timber was ruled out of Saturday’s fixture with an injury sustained on Boxing Day, while Riccardo Calafiori was forced out of the starting line-up with a problem suffered in the warm-up.Ben White and Cristhian Mosquera were both unavailable, too, as Declan Rice was deployed at the Emirates as an emergency right-back.