League One leaders Cardiff City landed a significant blow in the battle for promotion as they won at Bradford City to extend the gap between themselves and the Bantams in third place to nine points.

The Bluebirds strode to a commanding 2-0 first-half lead courtesy of David Turnbull's splendid curling 20-yard strike and Calum Chambers' neat backheeled finish.

Bradford got themselves back into contention after the interval as Jenson Metcalfe whipped in a stunning effort from almost exactly the spot from which Turnbull had scored.

The home side applied pressure in the closing stages, but Cardiff were able to cling on for a precious victory, which also moves them seven points clear of second-place Lincoln City before the Imps visit Luton Town later on Saturday.

Bradford were the first team to beat Cardiff this season, winning 3-1 in the Welsh capital in September.

The two sides have consistently set the pace at the top of League One, which is particularly impressive for Bradford when you consider they were two divisions below Cardiff only last season.

During the first half at Valley Parade, however, there was a gulf in class between them.

That was illustrated by the identity of Cardiff's goalscorers: Turnbull, a Scotland international who cost around £2m when he joined from Celtic, and Chambers, an England international who counts Arsenal and Aston Villa among his former clubs.

The fact those two were recalled to the team is evidence of the enviable depth Cardiff boast at this level, even after seeing more than 10 senior players leave following their relegation from the Championship last season.

Brian Barry-Murphy's men dominated possession – as they almost always do – and created several openings, before and after Turnbull found the top corner from Ollie Tanner's lay-off and Chambers flicked in from Tanner's low cross.

Cardiff were close to extending their lead after the break when Gabriel Osho saw a header cleared off the line but, after Bradford substitute Stephen Humphrys blazed over from Josh Neufville's cutback, the visitors had been warned.

The Bantams pulled a goal back in spectacular fashion as Neufville found Metcalfe and, from 20 yards, his first-time shot arced beautifully into the far corner.

That transformed the mood at what had been a subdued Valley Parade and, as Graham Alexander's side pressed forward intently, there were half-chances for debutant substitutes Louis Sibley and Harrison Ashby.

Cardiff could not control the game as they did in the first half and replaced top scorer Yousef Salech with centre-back Will Fish for the final five minutes.

This was a stern examination of the Bluebirds' promotion credentials, and they dug deep to take another important step towards an instant return to the Championship.