Royal Challengers Bangalore claimed a dramatic one-run victory over Delhi Capitals to prevail in a battle between two of the Indian Premier League's early pace-setters.

Both sides went into the match in Ahmedabad having won four of their opening five games and only the finest of margins could split them on the day.

RCB posted 171-5, led by a fine 75 not out from AB de Villiers, and then held on amid a late Delhi flurry as death bowler Mohammed Siraj limited the Capitals to 12 off the last over when 14 was the target to win.

It was Shimron Hetmyer's explosive 53 off 25 balls that threatened to turn the contest on its head, but he only faced one delivery in the final over and Rishabh Pant's efforts came up short at the other end.

It looked like trouble was in store for RCB, who were beaten soundly by Chennai Super Kings last time out, after captain Virat Kohli fell in the fourth over for just 12 runs and Devdutt Padikkal (17) followed him next ball.

Glenn Maxwell (25) and Rajat Patidar (31), who each scored a pair of maximums, helped to steady the ship but it was South Africa legend De Villiers who really upped the tempo.

His unbeaten knock included five sixes and three fours as he elevated his side to a far more competitive total, which the Capitals had looked set to fall well short of.

Their response was truly floundering by the time Prithvi Shaw's dismissal left them on 47-3 in the eighth over, with inspiration sorely needed from somewhere.

Up stepped Pant and Hetmyer, the latter going at a searing strike rate of 212 to have RCB nerves jangling.

But with Pant also well set heading into the deciding over, the skipper took the responsibility on his own shoulders and, though he reached 58 not out, his four off the last ball was not the kind of boundary Delhi needed.

Siraj keeps his cool

Handed the ball and the task of shackling two batsmen in good touch, Siraj proved equal to the task.

He only allowed four runs from the first four deliveries, leaving Pant needing a six that his otherwise excellent innings ultimately failed to produce.

"I was only thinking that my yorker's coming out well," said Siraj. "It's what I execute in tough situations, so I was confident in my yorker. That's all I was thinking about."

Destructive De Villiers

While Siraj's work with the ball ensured his side got over the line, it was De Villiers' destructive brilliance with the bat that gave the bowlers a target to defend.

This showing took him past 5,000 IPL runs, becoming just the sixth player to surpass that mark.

He was unsurprisingly given the man of the match award.