McGrath produced some old magic as he demolished the Royal Challengers and put his team in front immediately in the first over by removing Praveen Kumar for six runs.
The Royal Challengers, who went down to Chennai Super Kings by 10 runs in their last encounter again fell short by the same margin here.
The visitors were off to a poor start and lost their first three wickets for only 48 runs on the board. But then captain Rahul Dravid joined Jaques Kallis and both the batsmen blossomed in the company of each other to add 87 runs in 63 balls.
Just when the partnership looked threatening, Daredevils captain Virender Sehwag turned to McGrath who had already picked three wickets by then.
McGrath did not disappoint his captain and removed Dravid for a personal score of 38 which came off 30 balls. Dravid's innings included six boundaries and a lofted six at long-on off Shoaib Malik.
For his superb effort, McGrath was awarded man of the match.
Dravid's wicket did not help the visitors as the scoring rate kept on mounting and Royal Challengers finally succumbed to yet another defeat in the tournament as Kallis and Mark Boucher remained unbeaten on 54 and 31 respectively.
Earlier asked to bat first, Sehwag started in his typical fashion and raced to 24 off just 12 balls before a Ross Taylor throw found him short off his crease. But it only got worse for Royal Challengers from there as Gautam Gambhir and Shikhar Dhawan put on 98 runs for the second wicket.
Gambhir continued his superb form in Twenty20 cricket and hit a masterly 86 runs off 54 balls.
He was well complimented by the left-handed Dhawan who matched Ghambhir stroke by sroke.
The 98-run partnership was well crafted by both the batsmen and took just 60 balls as the Royal Challengers looked at the scoreboard helplessly.
Half way through the innings, Daredevils were 91 for one and scored exactly 100 runs in the last 10 overs. However, both the batsmen were helped by some luck on their side.
Gambhir was lucky to have escaped a valiant attempt by Dale Steyn when he was on 48 and utilised the opportunity to guide his team to a challenging total against Royal Challengers who have managed just one win from four matches.
The partnership was finally over in the 15th over when Dravid pulled off a magnificent catch at short mid-wicket to give Jaques Kallis his only wicket in the match.
It was hard time for Dravid's bowlers as Gambhir and Dhawan toyed with the bowling.
Praveen Kumar was the only bowler who looked to trouble the two batsmen. His four overs costed 24 runs but went wicketless.
However, his other compatriots could not make a huge impact with the ball with Kallis taking two wickets giving away 39 runs off his alloted overs while Dale Steyn and Zaheer Khan chipped in with a wicket each.
After the loss of Gambhir and Dhawan, the Daredevils' batsmen looked to continue the tempo but fell while doing so to finish 191 for five in their 20 overs.
Daredevils now have three wins from four games while Bangalore Royal Challengers have just one win from their five matches.