Indeed, the balance ultimately tipped the other way, Worcestershire carving through the lower orders even with no specialist spinner to clinch a victory that lifts them into title contention in fourth place.
Watched by chairman of selectors, David Graveney, James may have clinched a place on tour to the West Indies after his four-hour 130, the bedrock of Glamorgan's challenge. However, in chasing 374 to win, James needed the support of at least one more innings of substance, but none was forthcoming.
A fascinating finish was achieved without the need for a declaration after Worcestershire, 263 for 7 overnight, lost their last three wickets for 32 in 13 overs, the England off-spinner Robert Croft finishing with 4 for 98 from 42 overs.
With a minimum of 81 overs available, Glamorgan made the perfect start, James and partner Hugh Morris managing both to weather the new ball and keep in touch with the clock in an impeccable opening stand, putting on 115 in 30 overs before the latter was run out by Vikram Solanki's superb throw from extra cover as James chanced a single.
James lost another partner when Stuart Lampitt brilliantly caught Adrian Dale at slip, giving Tom Moody, the Worcestershire captain, a wicket from the first ball of a lengthy spell of respectable off-break bowling that suffered only when Waqar Younis went after him in some desperation towards the close.
The biggest blow, however, was inflicted by the seamer Gavin Haynes, who removed Mike Powell and, crucially, Matthew Maynard from consecutive deliveries, the Glamorgan captain perversely following his sublime unbeaten 161 with a first-ball duck.
James, dropped behind the wicket off Moody on 80 just before tea, completed his century against the same bowler with his 17th four. With Croft, who must attend an English Cricket Board disciplinary hearing in Bristol today before rejoining the England squad, chipping in, 78 runs were added for the fifth wicket, reviving Glamorgan's hopes.
But the odds shifted again when Croft drove the pace bowling prospect, Maneer Mirza, to mid-on for 39. Then, with 106 still needed, Glamorgan almost immediately lost Gary Butcher to a return catch followed by James, who holed out to deep backward square.
Younis ran out of partners as Adrian Shaw was run out by Lampitt's fine throw before 19-year-old Mirza, playing in only his third Championship match, took the last two wickets in seven balls.Reuse content