Erling Haaland has handed Manchester City a major injury boost after returning to training.Haaland, with 19 goals in all competitions this season, has been sidelined with a foot injury since City's 1-0 defeat at Aston Villa on 6 December.But the Norway international was pictured in training with the squad ahead of their third-round FA Cup clash against Huddersfield on Sunday.Jeremy Doku, who has missed his side's last eight matches with a muscular injury, also trained with his team-mates.Both players had previously been training individually.The imminent return of Haaland and Doku will send a warning to City's rivals with Kevin De Bruyne also stepping up his return.The Belgian star, who has been out of action since suffering a hamstring injury on the opening day of the season, made his comeback to the matchday squad an as unused substitute in City's comfortable 2-0 win over Sheffield United last weekend.Pep Guardiola's City trail Liverpool by five points in the Premier League with a game in hand.