Watch the moment fans clashed on the pitch after Celtic knocked Rangers out of the Scottish Gas Scottish Cup on penalties following a goalless draw. Dozens of Celtic supporters invaded the pitch after their side secured a 4–2 shoot-out victory. That sparked a response from hundreds of Rangers fans, who also made their way onto the field.

Flares were thrown as supporters from both sides spilled onto the pitch after Celtic's 4-2 win on penalties.

Celtic knocked Rangers out of the Scottish cup after winning a penalty shootout 4-2 following a goalless 120 minutes, before fans from both clubs invaded the pitch

As if the ugliness of the 120 minutes wasn't enough there was disgrace as Rangers and Celtic fans invaded the pitch at Ibrox, writes Tom English.

Watch the moment fans clashed on the pitch after Celtic knocked Rangers out of the Scottish Gas Scottish Cup on penalties following a goalless draw. Dozens of Celtic supporters…

After ugly scenes at Sunday's Old Firm derby, what do we know about the fan clashes and what could happen next?