Former Celtic midfielder Kris Commons believes Rangers will need to spend £100m to stand a chance of catching the Hoops, after Brendan Rodgers’ side thrashed the Gers 4-0 in the Scottish Cup semi-finals.

The defending champions, who beat Aberdeen in last season’s final, will face Motherwell at Hampden Park after a comprehensive win over their fierce rivals.

Tom Rogic opened the scoring in the semi-finals after 22 minutes, before Callum McGregor doubled Celtic’s advantage before half-time.

Moussa Dembele netted a penalty minutes after the break to put the game beyond doubt. Olivier Ntcham scored from the spot mid-way through the second-half to complete the rout.

Rangers haven’t beaten Celtic in their last 10-head-to-head meetings and the Hoops are currently 13 points clear of their rivals atop of the Scottish Premiership this season too.

The Bhoys have won seven league titles on the bounce since Rangers last sealed the Premiership crown and Commons believes the distance between the two sides is so vast.

The 34-year-old made 227 appearances for Celtic, contributing 161 goals,  and won five league titles, two Scottish Cups and one League Cup. He was highly successful as a Celtic player and tips his old club to stay dominant unless Rangers spend handsomely.

Commons said in his Daily Mail column:

“Before Sunday, I felt this Rangers team needed tens of millions thrown at it to have a chance of competing against Celtic. After seeing the performance, it could be £100m.

“If you brought in ten players on 15 to 20 grand a week for the next three years, including transfer fees, that could gobble up £70m. But that’s the kind of investment that’s now needed. They are so far behind their city rivals it’s incredible.”