You fear for Luton, as you would for a really good welterweight operating at light heavyweight. But on Saturday, not for the first time and not, surely, for the last, Mike Newell's side prevailed against a mightier opponent with some smart ducking and diving and nifty combination work.
As the Luton manager pointed out, his team is effectively operating in a "different league" to many other Championship sides in terms of resources. Although this victory lifted them to seventh - one behind their opponents, who dropped from the Premiership last season - Newell knows that to maintain their altitude his side need luck as well as judgement.
"It's a fact of life," he said. "On our day we are capable of beating anybody. But we have to be fortunate and hope players stay fit and free of suspension."
Rowan Vine gave another buccaneering display of the kind that has had the Kenilworth Road faithful in raptures in recent times, turning the game Luton's way with two goals within the space of a minute.
Vine opened his account from the penalty spot in the 27th minute after referee Jon Moss had harshly adjudged that Stephen Kelly had halted Lewis Emanuel's charge towards the byline unfairly. That followed DJ Campbell's opener for Birmingham, when he reacted first to a 14th-minute cross from the hyperactive right winger Neil Danns.
Birmingham's manager, Steve Bruce, was unhappy with the penalty award, particularly as his forward Cameron Jerome had had a very decent claim turned down in the opening minute when he was clearly impeded by Luther Barnett.
"Decisions like that win football matches," Bruce said. "The referee got it totally wrong." Newell conceded that the award was "a little bit harsh". It sparked his side into life, and they went ahead when Vine knocked in a loose ball from close range a minute later.
Birmingham drew level through a walloping drive in the 66th minute from Danns, whom Birmingham beat Luton to signing from Colchester this summer.
But as Birmingham pressed for a win, Luton caught them on the break and Ian Bell, a 71st minute substitute, struck his first goal for the club from Kevin Foley's right-wing cross.
Goals: Campbell (14) 0-1; Vine (27) 1-1; Vine (28) 2-1; Danns (66) 2-2; Bell (81) 3-2.
Luton Town (4-4-2): Beresford; Foley, Barnett, Heikkinen, Davis; Edwards, O'Leary (Bell, 71min), Robinson, Emanuel (Morgan, 56); Parkin, Vine (Feeney, 81). Substitutes not used: Keane, Brill (gk).
Birmingham City (4-4-2): Taylor; Kelly, Jaidi, N'Gotty, Sadler; Danns, Nafti (Larsson, 61), Muamba (Kilkenny, 56), McSheffrey; Jerome (Forssell, 69), Campbell. Substitutes not used: Doyle (gk), Tebily.
Referee: J Moss (W Yorkshire).
Booked: Luton Barnett.
Man of the match: Danns.
Attendance: 9,275.Reuse content