Phelan has been impressed by a number of individuals' performances, especially the new arrivals.
"Robin [van Persie] has come in and made an instant impact," he told manutd.com. "He's still chasing a little bit of fitness and is still in that settling-in period, but he's a top-drawer player and that's what we needed.
"Shinji Kagawa has had a few games and now knows what the Premier League is all about and he's obviously played in Europe quite a lot. You can see his work-rate and he's started to show some real intent with his football and what he's going to bring to this club so it's exciting on his part."