Player of the month for August Ryan Kent opened the scoring early before skipper James Tavernier sealed victory on his 250th appearance for the club.

Kemar Roofe and Scott Arfield rounded off the scoring midway through the second half but Gerrard will be left sweating after Leon Balogun, Ryan Jack, Brandon Barker and Alfredo Morelos all had to be replaced.

The Ibrox casualty concerns began in midweek with confirmation Joe Aribo could miss a further six weeks with an ankle injury that has already kept him out for a month.

United – who stay in eighth place – had Lawrence Shankland back on the bench after a similar lay-off.

But the game had not even kicked off when Gerrard had more to worry about.

Filip Helander was scheduled to start among the substitutes after reporting back from Sweden duty just 24 hours earlier but was hurried into the starting line-up at late notice when Balogun hurt himself in the warm-up.

Jack then went down 11 minutes in with an apparent recurrence of the calf issues which bothered him last term. Barker did not last much longer as he pulled up after chasing a ball into the corner.

Thankfully for the Rangers boss, his side had already taken the lead by this point.

Rangers had created little in the opening 13 minutes but Kent's trickery soon opened up United's defence.

Combining with Ianis Hagi on the edge of the box, the £7million winger carried on his stunning start to the new season as he sent Ryan Edwards one way, then another, before slamming through Benjamin Siegrist's legs.

Morelos was sent on to replace Barker but fluffed his first sight at goal as he failed to connect cleanly with Kent's cut-back.

But Rangers were two-up seven minutes before the break. Borna Barisic's cross took a nick off Luke Bolton but still managed to find Tavernier at the back post and he muscled Jamie Robson to prod home on his milestone run-out.

Roofe spurned a good chance to extend Rangers' lead moments into the second half as he fired straight at Siegrist.

The former Leeds forward was involved again as he put Morelos in behind, but Kent could not convert as the Colombian fired across the face of goal.

That proved to be Morelos' last involvement as just moments later he was stretchered off with a nasty wound on his thigh after being caught high by Edwards' shocking challenge.

Incredibly, referee Kevin Clancy did not even talk to the Terrors defender when he could easily have flashed red.

Siegrist repelled two more efforts from Hagi and Calvin Bassey but could do nothing after 68 minutes as Roofe got a toe to Arfield's strike to divert it home.

Ian Harkes almost shattered Rangers' clean sheet run with five minutes left as his fierce drive shook Jon McLaughlin's crossbar.

But it was the hosts who pounced again with three minutes remaining as Hagi teed up Arfield to slam in the fourth.