Fulham moved into pole position to seal a place in the Championship playoff final.
The London club was taking on Cardiff City in the first leg away from home.
But they emerged with a 2-0 victory at their rivals stadium, which gives them a great advantage for the second home leg.
The Cottagers are now in control of the tie and will hope to book their place in the final at Wembley.
Onomah scored in the second half, while Kebano netted in stoppage time, giving his team a much needed two goal advantage for the second leg.