Arsenal manager Mikel Arteta has welcomed Fabio Vieira back into the fold ahead of the Gunners’ return to Champions League action. The Arsenal boss, speaking at his pre-Porto press conference, admitted he was both happy and sad for the 23-year-old midfielder. Arteta said he was obviously happy because Vieira is back in training after missing several months following groin surgery in November. At the same time, the Arsenal boss is sad because the injury halted his momentum at a time when he was going from strength to strength. Arteta then pledged to “get the best out of” Vieira, as he is a play…