With five minutes remaining and the Second Division promotion rivals heading for a fourth successive stalemate, there seemed scant prospect of either producing tangible evidence to support claims of local superiority.
Suddenly, Stein scampered clear on to Kevin Russell's pass. Vale's trailing defenders appealed for offside and even Stein checked, but with no whistle forthcoming he homed in on the advancing keeper. As he pushed the ball wide of the sprawling Paul Musselwhite, the little striker went tumbling over his thigh.
Three-quarters of the 24,500 capacity crowd screamed for a penalty. The rest watched in numbed disbelief as the referee awarded one. Musselwhite, merely booked because Mr Watson judged that he had not denied Stein a scoring opportunity, furiously protested his innocence, but his neck was already in the noose.
Stein, ignoring the fact that he had been relieved of penalty-taking duties after a recent miss, promptly dispatched his 13th goal of the season. But was he fouled - or did he dive? The debate began immediately, fuelled by Central TV's 'Goals of the Day' which the managers watched together.
'I shouted 'penalty' the moment Mark went down,' Stoke's Lou Macari said. 'The fact that he went wide of goal doesn't detract when you see a keeper lean into him like that. The ref has to be right.' For Vale, John Rudge inevitably saw it differently: 'It was inconclusive. Stein looked offside to start with - he seemed to think so, too - and Musselwhite maintains he didn't bring him down.'
Stein's version of events did nothing to cool the controversy. 'I overran the ball,' he admitted. 'The lads were saying it was dubious, but I would never con anyone. The keeper made contact with me when he didn't need to make any challenge.' Musselwhite, who came into the side after the previous incumbent had rashly conceded a penalty, may indeed have been betrayed by inexperience.
Vale's frustration also owed much to the way they let a second- half lead slip. Paul Kerr struck a fine goal 10 minutes after coming on, only for Ian Cranson to head an instant equaliser. That opened up a tense, bruising game, and the commitment which is a characteristic of all Macari teams meant Stoke just about deserved to beat slicker but slower neighbours who have now won one of 13 derbies dating back 60 years.
Hundreds of home supporters 'celebrated' victory by invading the pitch, and had to be prevented from confronting the Vale contingent by mounted police and dog-handlers. The worst casualty was Vale's pride, though it was a sadly divisive end to an afternoon that began with the Victoria Ground united in applause for parading miners from a condemned pit.
Goals: Kerr (67) 0-1; Cranson (68) 1-1; Stein pen (85) 2-1.
Stoke City: Sinclair; Butler, Gleghorn, Cranson, Overson, Sandford, Foley, Ware (Russell, 47), Stein, Shaw, Beeston. Substitute not used: Regis.
Port Vale: Musselwhite; Sandeman, Sulley, Walker, Swan, Glover, Aspin, Taylor, Cross, Houchen, Van der Laan (Kerr, 57). Substitute not used: Porter.
Referee: J Watson (Whitley Bay).Reuse content