Adebola had a header superbly saved in the first half at Selhurst Park and the opening goal game in the 56th minute when Louis Carey, who had a short spell at City whilst Peter Reid was in charge, curled into the top corner.
Carey,then gave away a penalty three minutes from time which Ben Watson converted before a stunning thrity yard drive from David Noble gave The Robins the advantage to take into the second leg.
In the League Two play-off, Julian Joachim was involved for Darlington drew 1-1 with Rochdale.
Liam Daish was a Wembley winner as his Ebbsfleet side beat Torquay 1-0 in the FA Trophy Final. Chris McPhee scored the only goal of the game in the 45th minute after missing a penalty four minutes earlier.