THE toddler seemed overwhelmed as he emerged from the tunnel and on to the Tannadice turf.

In normal circumstances, little Shea Dillon would have wandered out clutching father Sean's hand but, with Dundee United's captain rested, the mascot was accompanied by Gavin Gunning instead. He was not best pleased. Eventually he just sat down on the pitch wailing as the bemused United players ambled past. "You can tell I was the only father in the team," said John Rankin, who had scooped the wee man up into his arms. "The rest of the boys didn't know what to do. I think they were worried he had a dirty nappy."

Father-of-two Rankin was able to laugh about it afterwards not just because of United's thumping win but because he has grown used to cleaning up after kids this term. It is his partnership with Paul Paton in front of United's back four that is allowing the talented youngsters in Jackie McNamara's side to express themselves and, indeed, the shield that the two midfielders provide is perhaps the main reason that the Tannadice side have gone from having one of the top flight's most porous defences last season, to the most resolute this.

To suggest the duo are a solely destructive presence would be grossly unfair, though. For all that United's feted forwards shone on Saturday, a compelling case can be made to suggest that Rankin's performance - on the occasion of his 100th appearance - was the most accomplished of all. Positionally astute and robust in the tackle, his passing was crisp and perceptive, and it was from his throughball that Nadir Ciftci opened the scoring.

That in itself was crucial, for until that point United played in a manner that has come to be familiar this term: enterprising and adventurous but unable to put the finishing touch to their work. Such profligacy cost them at Aberdeen the previous weekend and McNamara confided that he feared a similar scenario might have transpired against St Mirren had the goal not come when it did. Instead, Ciftci's effort removed any such doubts and heralded perhaps United's most eye-catching performance of the campaign.

The Turk was integral to that, his brace burnishing another excellent offering, but so too were Gary Mackay-Steven and Ryan Gauld completing the trio behind the willing but diffident Brian Graham. Further back, Radoslaw Cierzniak's handling was impeccable, full-backs Andy Robertson and Mark Wilson were full of adventure, and John Souttar and Gunning combined resolution with slick distribution in central defence. That United could deliver such a display having rested Stuart Armstrong, David Goodwillie and Keith Watson, as well as Dillon, speaks volumes about the depth at their disposal.

"It's the most exciting bunch that I've been involved with," admitted Rankin. "When you look at the talent here, it's incredible: Gauldy's 17, Soapy [Souttar] has the cigar out and is trying tricks, and they're fearless. The longer they can keep playing that way the better. I always say to people it's a joy because most of the time you are just watching the front four play and picking up the pieces for them when they lose the ball. With the ability they've got, if they go and work hard they can take us up the league - and they know that themselves - because at times we were sensational."

Their ability to be stoic, rather than sensational, is probably what United will need to show tomorrow when they travel to Inverness in the quarter-finals of the Scottish League Cup. As Rankin said, every team left in the tournament now feels they can emulate St Mirren's success in last season's final, but Danny Lennon's side are not one of them, the holders having been skelped by Queen of the South. That meek defence was one of several reasons Lennon was thought to be close to losing his job last month, only for seven points from nine in recent weeks to have eased the pressure. However, while Hearts remain 15 points adrift and appear the most likely candidates for automatic relegation, Saturday's defeat leaves St Mirren sitting in the play-off place and, on this evidence, lacking the tools to haul themselves to firmer ground.

For all United were excellent, the Paisley side were abject at Tannadice. They offered next to nothing in attack, were outmatched in midfield and debutant goalkeeper Marian Kello was exposed on countless occasions. "I was shouting a lot but the players maybe had their own ideas," said the frustrated Slovak. "I don't know if the manager had maybe told them things earlier in the week about how to play but we didn't defend properly. I've been here three days and I see a difference in the players in training and in matches. I have to get to know them, how they play and what they expect from me but that takes time."