Last updated on .From the section Scottish League Cup

Glenn Middleton was involved in all four Rangers goals, scoring two

Rangers thumped second-tier Ayr United at Ibrox to book a Scottish League Cup semi-final with Aberdeen.

Nikola Katic headed Steven Gerrard's side in front and Glenn Middleton doubled the lead before half-time.

Alfredo Morelos will be suspended for the last-four match after being booked but stabbed in Rangers' third goal, before Middleton completed the scoring.

Morelos' ban means Gerrard is shorn of his two first-choice strikers for the semi with Kyle Lafferty cup-tied.

The Northern Irishman is ineligible having already played for Hearts in this season's competition.

Magnificent Middleton sparks Rangers

Gerrard fielded a team showing six changes to that which dismantled St Johnstone on Sunday, but there was no sign of disruption.

The fulcrum was 18-year-old Middleton, who was a rapid and effervescent menace to the Ayr defence on his first start for the club.

The teenager had a hand in all four goals, first winning the corner from which Katic opened the scoring, then darting off his wing to gather Andy Halliday's beautiful lofted pass and slam past Ross Doohan.

Middleton's delivery found Morelos in the six-yard box, and the Colombian showed great power to spin Mike Rose and finish.

The Ayr defender was beaten again by Middleton, who made it 4-0 with an emphatic finish.

The winger might have completed a treble late in the game, but saw his shot hit the side netting.

Alfredo Morelos showed good power to net Rangers' third goal but will miss the semi-final

Hot-tempered Morelos hurts Rangers again

Morelos was sent off for dissent in Rangers' Europa League play-off first leg against FC Ufa last month, having already been booked seconds earlier for kicking the ball away.

That was his second red of the season, his first coming for aiming a kick at Aberdeen's Scott McKenna on the opening day of the Scottish Premiership campaign - although that sanction was subsequently downgraded.

The striker has delivered so much good this season - eight goals, industrious, unselfish performances - and earned his first international cap, but his petulance continues to cause Rangers problems.

He was caught late by Ayr's Jamie Adams, but unleashed a tirade at referee Bobby Madden, who promptly brandished a yellow card.

Morelos responded positively to the booking by showing all his attacking prowess in the hosts' third goal, but his flash of anger leaves the Ibrox manager with plenty to ponder for the semi-finals.