Lowly Doncaster Rovers have ended Reading's eight-game winning streak at the Keepmoat this evening.
The high-flying visitors began strongly and almost took the lead in the third minute when Alex Pearce headed Ian Harte's corner towards goal only to see it cleared off the line by El Hadji-Diouf.
Reading continued to threaten from set pieces, with Kaspars Gorkss and Mikele Leigertwood wasting the best opportunities before the home side took a surprise lead in the 27th minute.
Diouf crossed from the right and Kyle Bennett was on hand to tap home and put Rovers one ahead.
Noel Hunt almost levelled the scores five minutes before the interval but saw his header well saved by Carl Ikeme.
The visitors equalised six minutes into the second period through Pearce who headed home a Harte corner after being left unmarked at the back post.
Brian McDermott's men pushed for their ninth straight win but were unable to find a second in the latter stages.
A point for Reading means they move above West Ham into the automatic promotion places while Donny also climb a place to 22nd and are three points from safety.