Sehwag had played cautiously on Sunday to reach 21 but on Monday he blasted the Uttar Pradesh bowlers repeatedly, peppering the off-side field as he hit 19 boundaries in his 165 ball knock.
It was solely due to Sehwag's heroics that Delhi managed 322 in their second innings, leaving UP with a target of 155 to win in 50 overs.
Chasing the target, rival skipper Suresh Raina, who was on Monday axed from India's Test squad, hit a quick fire 37 but once he was holed out in the deep by Sangwan off Ishant Sharma's bowling, UP looked like going out of steam.
When Raina got out, UP still needed around 40 runs. Delhi's stand-in captain Gautam Gambhir along with senior bowlers Ashish Nehra and Ishant Sharma indulged in time-wasting tactics under fading light with umpire Amish Saheba telling them to speed things up.
It was then left to Arish Alam (15 no) and Ali Murtaza (14 no), who batted superbly in fading light, to take UP home. The duo hit Ishant Sharma for nine runs and then struck Vikas Mishra for a couple of boundaries to win pocket the match for the home team.
It was Murtaza's spanking square drive off a Sumit Narwal delivery that levelled the scores before Arish's late cut off Mishra ended the match.
The fourth day's play, however, was all about Sehwag's batting. Sehwag, who ran out of partners, got good support from Pradeep Sangwan (21) towards the end as he raced to his century in 146 balls.
Sehwag was in such mood that he smashed seven boundaries adding to the three he hit overnight as he went on to complete his half century.
The bowler who suffered most was Imtiaz Ahmed as the star batsman hit him in the arc between cover and point region.
Bhuvneshwar Kumar wasn't spared either and at no point did it look that Sehwag was in any sort of pain. Praveen Kumar was the only bowler who got some respect from Sehwag as he was hit for only one boundary over mid-on.
Sehwag completed his century before lunch when he cut Imtiaz towards point boundary for two runs to complete his 37th first-class century.
Interestingly, this was his eighth first-class century for Delhi and the first one for the state side after nearly six years. He last scored a 100 for Delhi way back in January 2007 against Haryana at Rohtak.
What was important during Monday's knock was the effortlessness that has been synonymous with the 34-year-old. The UP attack didn't have much quality but that doesn't take away anything from Sehwag's effort as it was a knock from a man under pressure. He was also not 100 percent going into second innings and came in only at No 6.
The most important factor is requisite confidence that he will carry going into the England series which starts on November 15 in Ahmedabad.
Credit should also go to the UP team for their lion-hearted effort. Raina promoted himself up the order in place of injured Mohammed Kaif which was an indication that UP were going for the chase.
Raina's push through the cover off Ashish Nehra's bowling was the best shot of the UP innings. He also hit a beautiful square drive off Ishant's bowling.
First innings centurion Mukul Dagar, with a well-made 37, set the tone for the chase adding 54 for the first wicket with Tanmay Srivastava (26). Raina took over from there but the final credit should go to Murtaza and Arish for finishing the match with flourish.
Delhi 235 & 322 (V Sehwag 107, M Manhas 65, B Kumar 4/94, I Ahmed 4/112).
UP 403 & 158/4 (M Dagar 35, S Raina 37). UP: 6 points; Delhi 0 (New rules: Outright win 6 pts; 10 wkts/Innings win: 6+1=7).