Celtic missed the chance to extend their lead at the top of the Scottish Premiership to six points after being held to a frustrating 2-2 draw by Dundee United at Celtic Park on Wednesday night.

With Hearts and Rangers also drawing 2-2 at Tynecastle, Martin O’Neill’s side had the opportunity to open up a bigger advantage over their Glasgow rivals.

Celtic remain four points clear of Rangers after 11 league matches, but Wednesday represented an opportunity they will feel should have been taken.

O’Neill named an unchanged starting eleven following Sunday’s victory over Hibernian, and Celtic made the breakthrough after 18 minutes.

Callum Osmand’s cross was headed down by Benjamin Nygren before Kasper Høgh laid the ball into Camilo Durán’s path.

The Colombian made no mistake, finishing confidently to put Celtic ahead.

It was Durán’s 12th goal of the season and appeared to have given the home side a platform to take control.

However, Dundee United responded strongly.

Jack Walton’s goal was briefly under pressure, with Nygren striking the post from distance, but United were finding far too much space when they moved forward.

Zac Sapsford equalised in the 28th minute, meeting Lyall Cameron’s cross with a header that beat Sam Johnstone.

Just three minutes later, Neil Farrugia put Jim Goodwin’s side ahead following another dangerous delivery into the Celtic penalty area.

Liam Scales was unable to prevent the ball crossing the line, and a VAR check confirmed the goal would stand.

The manner of the turnaround was particularly frustrating. Having worked their way in front, they conceded twice in quick succession and allowed United to dictate too much of the opening period.

O’Neill responded at half-time by withdrawing Høgh and Osmand, introducing Jota and Haissem Hassan.

The changes immediately gave Celtic more attacking width, with Durán moving into the central striking role.

Celtic’s pressure eventually paid off in the 65th minute.

Jota combined with Mika Baur at a short corner before delivering an excellent cross into the area, where Scales rose to head home the equaliser.

The goal brought Celtic level, but there was still work to do.

Baur subsequently forced another save from Walton, while Nygren wasted a promising attacking opportunity with an effort that drifted wide.

United remained dangerous themselves, with Johnstone required to make saves from Michael Forbes and Abdoulaye Yoro.

Despite introducing fresh players late on, Celtic were unable to find a winner.

The frustration was made worse by events at Tynecastle.

Hearts and Rangers shared four goals in their own Premiership game, meaning Celtic could have moved six points clear of the Ibrox side with a home victory.

Instead, the advantage remains at four points.

Celtic have enjoyed an impressive domestic start under O’Neill, but the defensive problems exposed by United will concern the manager.

The visitors had enough opportunities to punish Celtic’s first-half defending and continued to threaten after the equaliser.

O’Neill will also have questions to consider in attack.

Høgh’s goalless run continued, while the introductions of Jota and Hassan made a clear difference to Celtic’s ability to create openings.

Celtic now travel to Falkirk on Sunday while Rangers and Hearts are involved in League Cup semi-final action.

That gives the Hoops another opportunity to extend their lead before their rivals return to Premiership duty.

But after Wednesday’s display, O’Neill will want considerably more from his players than the second-half recovery that rescued a point against Dundee United.