Report: Blues 1-1 Watford
John Eustace's side were good value for their point on an occasion when George Hall struck his first senior goal.
The 18-year-old showed tremendous composure to find the bottom corner after 19 minutes in front of the Gil Merrick.
That landmark moment was cancelled out by Ken Sema's second-half effort, but this did not dampen Birmingham City's spirit or weaken their resolve and they looked equally as likely to score a winner.
The Head Coach made two changes to the side that started at Cardiff City on Saturday. Marc Roberts missed out altogether and Alfie Chang was on the bench, meaning Josh Williams and George Hall came into the team.
Neither side was able to assert themselves on proceedings in the opening ten minutes, with Blues limiting the recently-relegated visitors to speculative efforts from distance.
Watford did have the game's first genuine chance approaching a quarter of an hour. Joao Pedro lifted a cross from the left and Vakoun Bayo, who found himself in space, headed well off-target.
They would go significantly closer from a corner shortly after, but Bayo's second miss from a header - hitting the post after Craig Cathcart had got the first contact - served as a valuable wake-up call for the hosts.
Eustace's side responded in the best possible fashion to these scares and opened the scoring in style. Scott Hogan sped down the right and rather than crossing blind, picked his moment to spot the late arrival of Hall who swept the ball into the far corner like a seasoned pro.
However, as quickly as they had gone behind, the Hornets reminded the B9 crowd of their capabilities and a heroic last-ditch clearance from Dion Sanderson, that had referee David Webb checking his hawkeye-enabled watch, denied Mario Gaspar.
Overdue rain in the West Midlands was greasing the playing surface and events continued to gather pace. Juninho Bacuna showed a tremendous speed of thought to both identify and execute a volleyed back heel onto Troy Deeney who stung the palms of Daniel Bachmann from 25 yards.
The first period would then end in bizarre fashion, with Eustace booked for attempting to enable a quick throw as Hamza Choudhury, who also received a yellow card, kicked the ball away.
HALF-TIME: Blues 1-0 Watford
The goalmouth action continued after the break and a combination of perseverance and neat footwork gave Hogan an early sighter. He worked the ball into the box and kept the Hornets' stopper honest with a low, zipping effort on his left foot.
Although as the precipitation intensified, Eustace would have perhaps been more pleased with the determination of his men to disrupt the Golden Boys' flow and keep things watertight.
Bacuna was allowed to roam thanks to Jordan James and Hall screening the defensive line diligently, whilst fellow teenager Josh Williams locked down the right flank.
Such were the limitations imposed by blues that when Watford did level in the 63rd minute, Sema's low shot required at least one deflection to squeeze its way into the net.
Refusing to let Rob Edwards' team gain momentum from the equaliser, Birmingham fashioned a chance heading into the final 20 and Deeney's well-hit volley forced Bachmann to concede a corner.
From then on in, it was a cat and mouse contest, with both teams juggling the merits of taking a point or pushing for more. Blues were positive, introducing Lukas Jutkiewicz and Jonathan Leko for the climax.
As it was, nobody could find a moment of magic at the death despite Bacuna's late centre crying out for a royal blue shirt to finish it off.
Hall followed up his effort at Burton Albion in pre-season with his first professional goal on a proud night for him, his family and the Club's Academy.
The draw takes Blues' early tally to five points as they remain unbeaten on home turf.
Blues (3-5-2): John Ruddy, Maxime Colin, Dion Sanderson, Auston Trusty, Josh Williams, Jordan James, Juninho Bacuna, George Hall (Alfie Chang 79), Przemyslaw Placheta (George Friend 90+2), Scott Hogan (Lukas Jutkiewicz 85), Troy Deeney (Captain) (Jonathan Leko 85).
Substitutes not used: Neil Etheridge, Jobe Bellingham, Jonathan Leko, Sam Cosgrove.
Booking: Eustace 45+3, Sanderson 81.
Watford (3-4-1-2): Daniel Bachmann, Christian Kabasele, Francisco Sierralta, Craig Cathcart (captain), Mario Gaspar, Edo Kayembe (Keinan Davis 89), Hamza Choudhury, Ken Sema (Joseph Hungbo 89), Yaser Asprilla (Dan Gosling 76), Vakoun Bayo (Rey Manaj 55), Joao Pedro.
Substitutes not used: Maduka Okoye, Jeremy Ngakia, William Troost-Ekong.
Booking: Choudhury 45+3.
Referee: David Webb.
Blues continue their St. Andrew's schedule by welcoming Wigan Athletic on Saturday, kick-off 3pm, before a clear midweek ahead of a trip to Rotherham United seven days later, kick-off 3pm. August is then rounded off back in B9, with Norwich City the visitors in a fortnight's time, kick-off 7.45pm. Tickets are on sale now for both fixtures - click here to buy!