Former Celtic player Oh Hyeon-Gyu came back to haunt Rangers as his goal secured Genk a 1-0 win in their Europa League opener at Ibrox.

The pressure continues to build on Russell Martin, whose side also saw Mohamed Diomande sent off in the first half, giving the hosts a mountain to climb.

Rangers started well, with John Souttar coming closest to an opener in the 17th minute as his thumping header was brilliantly cleared off the line by an acrobatic Bryan Heynen.

Moments later, Jack Butland was left stranded at the other end as Patrik Hrosovsky's bending effort smacked his right post.

Rangers were then denied a penalty for a handball shout against Joris Kayembe before they were reduced to 10 men in the 41st minute after Diomande caught Zakaria El Ouahdi high on the shin with a poor tackle.

James Tavernier was then penalised for clipping Yaimar Medina in the box, but Butland kept Rangers in the game in the seventh minute of first-half stoppage time, denying Oh from 12 yards.

Genk piled the pressure on after the break and got their reward 55 minutes in, with Jarne Steuckers' throughball cutting open Rangers' defence before Oh confidently turned past Butland.

The South Korean thought he had doubled Genk's lead 14 minutes later after poking in Hrosovsky's low squared cross, but the Slovakia international had strayed offside in the build-up. That did not cost the visitors, though, as they held on for a narrow win despite Rangers' late pressure.

Data Debrief: Rangers fall to old foe

Oh made just 52 league appearances for Celtic during his two-year spell in Glasgow, but failed to hit the back of the net against Rangers in that time.

He put that right on Thursday, though, and led Genk's attack in style, topping the charts for shots (seven), expected goals (2.24 xG), touches in the opposition box (11) and 'big' chances (five).

Oh could easily have had more goals, and Rangers were indebted to Butland, who has saved five of the last six penalties he has faced in all competitions (excluding shoot-outs), including both in 2025.