Mark Knopfler and Emmylou Harris, Wembley Arena, London <!-- none onestar twostar threestar fivestar -->

It's hardly in the spirit of the enterprise, is it? Mark Knopfler and Emmylou Harris release a heart-warming country duets album, All the Roadrunning, and choose to perform it in the intimate surrounds of... Wembley Arena. Though Harris's voice and Knopfler's guitar prowess can make even the least inspiring surrounds seem convivial, you feel for the visually disenfranchised punters up in the gods at this hangar with seats.

"I must have done something right in my life to end up playing with Mark Knopfler tonight," Harris says. Her and Knopfler's approach to the duet is more question and answer than unison or harmony, but, as one critic put it, his voice can act like an easy chair for hers to recline on. This is apparent on the touching, 9/11-inspired "If This Is Goodbye", but "Red Staggerwing", an early set highlight, takes a different approach, the pair whooping it up on a stirring, Cajun-style courting song.

The duo's backing band are fantastic, the kind of seasoned, versatile outfit you could imagine nailing the soundtrack of O Brother, Where Art Thou? in their sleep. It is a measure of Knopfler's virtuosity that he holds his own with these US talents. On "I Dug up a Diamond", you are reminded just how special his playing can be, his plucked, fingers-only approach accessing gradations of timbre and subtlety that are unique and seductive.

There is plenty of variety in the set, too, Knopfler happy to take a back seat while Harris sings some solo hits. Pleasingly, there are also choice dips into the Dire Straits back-catalogue. An extended piano intro disguises "Romeo and Juliet", but then Knopfler starts picking its familiar chords on his silver Dobro guitar, and his craggy, half-parlando vocal kicks in.

After the closing lullaby that is Knopfler's "Shangri-La", the eight musicians on stage link arms and take a communal, music-hall-style bow. Knopfler and Harris soon return to encore as a duo. Fortunately, what follows isn't "Sultans of Swing", but rather "Why Worry?", a simple ballad with a sentiment and melody that wouldn't sound out of place on a Hank Williams record. It's the most intimate moment of the evening, and the punters are hitting speed-dial again.