The Tigers will go into Wednesday night's Championship Play-Off Semi-Final second leg in control after goals from Nick Barmby and Dean Windass gave them a 2-0 win against Watford in the first leg at Vicarage Road on Sunday afternoon.
Barmby and Windass struck inside the opening 25 minutes to move City a decisive step closer to their first-ever appearance at Wembley.
Phil Brown made two changes to his side.
Dean Marney missed out through injury and was replaced by Barmby while Richard Garcia returned after recovering from a shoulder problem to take the place of Caleb Folan who dropped to the bench.
The changes meant City reverted to a 4-4-2 formation.
Bryan Hughes moved into the middle of midfield as Barmby operated down the left with Garcia on the right.
Watford started brightly and thought they had taken the lead in the fourth minute when Dan Shittu headed home from a corner, but the referee harshly disallowed the effort after spotting an obstruction by Leigh Bromby.
Jobi McAnuff also saw a shot deflected just over, but it was City who took the lead in the eighth minute.
A mix-up between Shittu and Mat Sadler on the right allowed Fraizer Campbell to advance into the box and when he pulled the ball back, Barmby was on hand to calmly side-foot the ball into the bottom corner of the net via the goalkeeper's out-stretched hand.
Watford continued to attack and an interesting run from McAnuff carried him into the City penalty area before crossing to the near post, but Nathan Ellington couldn't apply the finish.
The Tigers doubled their lead on 23 minutes with a well-worked goal. Garcia's superb cross-field pass found Barmby and he then released Andy Dawson who had made an overlapping run to his left.
His cross found Campbell and when his header was deflected onto the bar by Bromby, Windass reacted quickest to nod the loose ball into the net from close range.
Dawson showed his defensive worth five minutes later, throwing himself in front of Ellington's shot to deflect it wide.
From the resulting corner, City countered and when Campell found Windass in the box, the veteran took too many touches before seeing his effort blocked.
McAnuff went close on 37 minutes after cutting in from the left, but his shot was magnificently turned over by Boaz Myhill when the ball seemed destined for the top corner.
Campbell was booked a minute before the break for rightly disputing where Watford were about to take a free kick from, the outcome being the home side taking the set piece ten yards in front of where it should have been.
In added time, Myhill was forced to tip Tommy Smith's shot from the edge of the box over the bar. City defended the corner, bringing the first half to a close.
Half Time: Tigers 2-0 Watford
Watford began the second half on the attack and came close when Ellington's looping header dropped onto the top of the bar before going over, although the referee inexplicably awarded a corner.
The home side were putting the pressure on City and Myhill had to produce an outstanding save to deny Sadler after he connected well with Shittu's cross.
But their hopes were dealt a further blow on the hour when captain John Eustace was sent off.
A wild challenge on Garcia from Eustace started a confrontation between both sets of players and when Eustace began pushing Ian Ashbee, he was shown a straight red card.
Watford then lost Shittu to a hamstring injury and he was replaced by Jay DeMerit.
City went close to a third goal moments later but Campbell's shot went just over before Barmby, who had been a menace to Watford throughout, was replaced by Craig Fagan.
Myhill was forced to save Smith's effort with his legs before the Tigers made their second change as Folan replaced Windass.
Campbell should have extended City's lead on 72 minutes after springing the offside trap, but Richard Lee stood up to his effort before Garcia fired an effort over from the edge of the box.
That was Garcia's last involvement as he came off to be replaced by Nathan Doyle, who took up an unfamiliar position on the right wing.
Myhill had to beat away a shot from substitute Tamas Priskin as Watford continued to look for a way back into the game before Doyle's shot flew straight at Lee at the other end.
Doyle was getting involved in the action and he was unlucky to see his lovely curling shot with his left foot come back off the post in the 82nd minute.
The home side continued their search for a goal with first Bromby and then Priskin going close.
In added time, Campbell latched onto Doyle's long ball before seeing his goal-bound effort tipped wide by Lee.
Tigers (4-4-2) Boaz Myhill; Sam Ricketts, Michael Turner, Wayne Brown, Andy Dawson; Richard Garcia (Doyle 74), Ian Ashbee [captain], Bryan Hughes, Nick Barmby (Fagan 64); Fraizer Campbell, Dean Windass (Folan 69).
Subs: Matt Duke, Nathan Doyle, Simon Walton, Craig Fagan, Caleb Folan.
Bookings: Campbell 45
Watford (4-4-1-1) Richard Lee; Lloyd Doyley (O'Toole 74), Leigh Bromby, Dan Shittu (DeMerit 62), Mat Sadler; Lionel Ainsworth (Priskin 74), John Eustace [captain], Lee Williamson, Jobi McAnuff; Tommy Smith; Nathan Ellington.
Subs: Mart Poom, John-Joe O'Toole, Adrian Mariappa, Tamas Priskin, Jay DeMerit.
Bookings: Priskin 79
Sent-Off: Eustace 61 (violent conduct)
