Hendon on Boro defeatO's head coach was extremely pleased with his side's showing despite a 3-1 pre-season defeat to Championship outfit Middlesbrough.
Albert Adomah gave Aitor Karanka's side a 1-0 lead at the break, before it was extended by Adam Forshaw in the second period.
Striker Paul McCallum, fresh from scoring against Braintree Town on Friday, notched his second goal in as many games to reduce the deficit, before Boro sealed the victory through Kike.
And though his side may have lost, Hendon was encouraged by the O's performance throughout the contest.
"It was a very good first half from us and we adapted well against a top Championship side, but they managed to score just before the break with a well-taken goal," he told leytonorient.com
"We changed things around for the second half and gave a few of the youngsters some big match experience and although we went further behind Paul pulled one back for us only for them to add a third.
"But on the whole I was encouraged by our performance against a side that was so close to promotion to the Premier League last season."
And while it is only pre-season, Hendon was delighted to see summer signing McCallum notch his second goal of pre-season.
"That's Paul's second of the campaign and that gets in a good frame of mind ahead of the season," he added.
"He's come in and settled in straight away. He is a goalscorer at the end of the day and it is nice to see him hit some good form early on. Ollie Palmer also impressed, but on the whole it was a solid performance."
The O's will continue to train out in Malaga for the remainder of the week, before facing another Championship side, Huddersfield Town, on Saturday at the Terriers' La Cala resort.
The kick-off for the fixture has now been changed to 10.30 am local time (9.30am UK time).
Orient v Boro: Grainger, Clohessy, Baudry, Trialist, Trialist, Turgott, James, Moore, Trialist, Simpson, Palmer.
Subs: Trialist, Woods, Clarke, Ling, Lee, Pritchard, Cox, McCallum, Kashket, Semedo.