Bruno Guimaraes is back in training as Arsenal prepares for their Champions League match against Napoli later this week. The 28-year-old Brazilian joined the club in the summer for £75 million, moving from Newcastle United. Despite his high-profile arrival, Guimaraes has yet to make a league appearance for Arsenal and was only named on the bench during the recent match against Chelsea. He did not play in that game but is hoping to get some playing time in Naples this week. Jurrien Timber is also progressing in his return to fitness, training with his teammates at London Colney today. The Netherlands international has been sidelined since March due to a groin injury that required surgery in the summer. Manager Mikel Arteta said Timber is in "really good condition" and is hopeful of being back in the squad soon. Cristhian Mosquera will remain out of action for Arsenal as he continues to recover from a muscle injury that kept him sidelined during the recent win over Chelsea. Meanwhile, William Saliba is still a long-term absentee, continuing his recovery from a back injury that has kept him out of the team for an extended period. Arsenal's squad is set to travel to Naples later today, with manager Mikel Arteta expected to hold a press conference on Tuesday evening to speak about the upcoming match and the team's current situation.