The Green Mountain Wolves had two players dismissed either side of the interval.
Winger Osama Al-Sayed received his marching orders just before the break as he collected his second booking for diving.
Defender Mohamed Gamal was sent off for a tough tackle on Ahli midfielder Ahmed Hassan, three minutes past the hour mark.
However, Contractors battled to hold Ahli to a goalless draw. Radwan thinks the one-time Egyptian champions could have even emerged winners from Saturday's game
"We were the better side in the first half," Radwan told the post-match press conference.
"We also wasted several clear-cut chances that could have put us in the driving seat against Ahli.
"It was difficult for us in the second period, but my tactics paid off and we managed to maintain the goalless score."