Yadav had finished as the third highest wicket taker in the February-March World Cup with 18 victims from eight games.
On Monday Yadav returned impressive figures of 4-0-18-2, getting his successes in the 18th and 20th over of the innings.
The Nagpur born right arm pacer conceded just five and three runs respectively in his two ultimate overs, enabling his side restrict the Delhi batsmen to a modest 146 for 8.
Askd about the yorkers he bowled in the last two overs, Yadav said: “If I'm bowling length in the last overs it's very easy to hit sixes, that's why I was bowling the yorkers."
Knight Riders skipper Gautam Gambhir also lauded Yadav no end. "A lot of credit needs to go to the bowlers, especially Umesh, he's been unbelievable, especially that last over he bowled.” Gambhir said it was a luxury to have bowlers of the calibre of Yadav, Morne Morkel and Sunil Narine in the same team.