Once upon a time, clubs from the same league would never play each other during pre-season.Things have changed, though, and Premier League clubs are constantly facing off overseas before the campaign kicks off.So far, we’ve seen fixtures like Liverpool vs Manchester City, Liverpool vs Manchester United and, last night, Arsenal faced Chelsea.We can never read too much into pre-season friendlies but it’s a bonus to catch a glimpse of how preparations are going with the new season just around the corner.And its a new era for both Arsenal and Chelsea.While Unai Emery has the tough task of replacing Arsene Wenger, Maurizio Sarri has taken over from Antonio Conte - who won the Premier League and FA Cup during his two seasons in charge.And having only been appointed on July 13, Sarri has a lot of work to do in a short space of time.He may have brought Jorginho with him from Napoli but that’s the only bit of business the club have done so far.On Wednesday night, Emery got the better of Sarri with Arsenal winning their International Champions Cup clash on penalties.But there was one massive bonus to come out of the match for Chelsea in the form of Callum Hudson-Odoi.The 17-year-old has been very impressive during pre-season and he demonstrated that once again against the Gunners.His pace caused Hector Bellerin - of all people - all sorts of problems and he looked incredibly exciting.Don’t believe us? Check out his individual highlights against Arsenal and you’ll be very impressed - remember he's just 17!

WATCH: HUDSON-ODOI'S HIGHLIGHTS VS ARSENAL

Hudson-Odoi’s performance certainly didn’t fail to get Chelsea fans excited. Have a look at some of the best reaction to his display:

In fact, the forward’s performance may have convinced Sarri to give him a chance in the first-team rather than loan him out.

And his display also prompted the Telegraph to write: “Callum Hudson-Odoi capped what has already been an outstanding pre-season with a wonderful individual display that has helped convince Sarri that he should stay with the senior squad rather than go on loan next season.

“Playing off the left in Eden Hazard’s usual role, Hudson-Odoi’s pace and willingness to run directly will have surprised nobody who has worked with him through Chelsea’s academy but it certainly left Arsenal right-back Hector Bellerin reeling.”

He’s certainly a youngster worth keeping a very close eye on this season.