The Gunners were off-colour for the majority of the first half and could have conceded on a couple of occasions before Sebastian Vasquez put the hosts in front.
They belatedly found their feet in the closing stages of the first half and equalised through Carlos Vela, with no further goals in the second half as both sides made wholesale changes.
Greentown had the first chance with just 90 seconds on the clock, Wang Song breaking clear only to be denied by Vito Mannone's legs.
Paulo Pezzolano then rapped the post in the 14th minute as poor Arsenal defending allowed him time to line up a curling shot.
The opener did come after Mannone blocked an initial attempt on goal following a deep free-kick, only to see Vasquez stroke the loose ball home.
Arsenal tried to hit back and good work from Bacary Sagna teed up Samir Nasri, starting despite the speculation over his future, with the Frenchman volleying low and just just wide of the post.
The leveller came on the stroke of half-time when Robin van Persie and Andrey Arshavin combined well in the penalty area, resulting in the Dutchman's side-footed attempt being bundled to Vela, who had a tap-in.
Arsene Wenger made a full compliment of changes at the interval and while Arsenal were more solid in possession they never got going in attack.
A couple of chances for Aaron Ramsey and one Theo Walcott header over the bar were as close as either side got to a winner.