Leyton Orient recovered from falling a goal behind to run out 4-1 winners over Sky Bet League Two newcomers Sutton at Brisbane Road.
Harry Smith notched a brace after Theo Archibald had cancelled out the opening goal of the match by Isaac Olaofe before Tom James put the icing on the Orient cake with the fourth goal in stoppage time.
The visitors took a deserved lead on 18 minutes when Olaofe robbed Shad Ogie and sent his shot into the top corner.
But that brought Orient to life and they levelled in the 30th minute when Archibald stabbed the ball home from close range after a long throw into the box from James.
Within a minute of the second half starting, Smith nodded the ball home after visiting keeper Dean Bouzanis spilled a cross.
Smith extended the lead in the 83rd minute with a fantastic strike when a throw was cleared to him and he drove an unstoppable left-footed volley into the net from 25 yards out.
Then, with time running down, a short corner was played to James and he beat the keeper at the near post.