Having gone into the break a goal down following a 43rd minute penalty, Sotiriou levelled the tie with a calm finish 10 minutes after the restart. Cambridge did not wait long to restore their lead however as they poked home from a corner just after the hour mark.
In a side consisting mainly of young professionals, Assistant Coach Ross Embleton took charge of the clash against League Two opposition with Head Coach Steve Davis watching from the stands.
Following a cagey opening few minutes goalkeeper Sam Sargeant was called into action, producing a strong stop to deny a Cambridge forward before the rebound was blocked by a fellow U’s player.
The O’s struggled to create many chances throughout the first half, but with just over 10 minutes of the half remaining produced a lovely move which resulted with Toby Stevenson’s cross being brilliantly touched away with striker Sam Dalby waiting to apply the finish at the back post.
It looked as though the sides would go into the break goalless, but with two minutes until the interval Cambridge took the lead from the penalty spot after Sargeant was adjudged to have tripped the U’s forward as he look to round the shot stopper.
After the break it was nearly 2-0 to the visitors, but Myles Judd was well-positioned to head off the line and two minutes later the O’s were level.
Excellent play from Dalby saw the young forward release strike partner Ruel Sotiriou, who took a touch before stroking the ball under the Cambridge goalkeeper to equalise on the 55th minute.
Moments later Sargeant was called into action as he produced a stunning stop to parry a close-range effort behind for a corner.
The Orient ‘keeper was unable to prevent Cambridge from restoring their lead on the 61st minute however, as a U’s corner was bundled home at the back post.
With 20 minutes remaining Freddy Moncur was then denied by a superb one-handed stop, as the Cambridge goalkeeper reacted brilliantly to thwart the midfielder after he had latched onto substitute Charles Clayden’s cross.
Unable to force an equaliser, Orient continued to push forward in the closing stages as Dalby saw an 88th minute header held for what proved to be the final chance of the afternoon.
ORIENT: Sargeant, Judd, McLean (Perkins 87), Clark, Stevenson (Camilo-Tayaca 73), Ochieng (Haxhiu 73), Moncur, Barker, Benyoucef (Alderson 64), Sotiriou (Clayden 64), Dalby
GOAL: Sotiriou (55)