The versatile full back is vying for a regular first team spot in Thomas Tuchel's squad ahead of the new season.
Tuchel recently admitted he was impressed by returning loan stars and their effort during pre-season training so far.
"Near the start of the season I got Covid and after I got an injury, so I started to play in December," Zappacosta said about last term, per the club website.
"But for me it's been a good season because I scored four goals, and it's been good because we were fighting relegation and when I got back in December we had seven points, but I'm really happy that the team finished in the middle of the table.
"So it's been a tough season but a good one.
"It has been a while that I've been in Italy so it's really good to be back here and work with some old friends and the coach as well, because he's a really good coach and we have been just trying to do what he's asking us.
"This pre-season, it's quite hard, but it's good pushing now just to be fit for the start of the league."
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