However, not once did he panic and ultimately reached the milestone in the penultimate over of India's innings.
India did well to push the match into the final over - and with England needing 20 off two overs, then 12 off the last would have still fancied their chances - but their poor start with the bat ultimately cost them after losing three wickets in the Powerplay.
Watch the first one-day global in the three match series between England and India, live on Sky Sports Cricket from 12pm on Thursday.
And no-one fought harder than Hales himself, as he clubbed England over the line with 58 not out from 41 balls to atone for his momentum-squandering knock of 8 from 18 in the opening match of the series.
With the score being below par, India's bowlers took it on their shoulders to make the most out of the match.
Ben Stokes is available again after the hamstring injury which has ruled him out of England action since the first Test against Pakistan in May. He slammed Bhuvneshwar Kumar to a six on the first ball of the 20th over and then hit a boundary to make sure England reach target easily. The Indian captain began to gain in confidence as he hit another six off Plunkett before he fell victim of Jordan in the 15th over, caught and bowled by the bowler in a soft dismissal.
Three terrific catches - one from Jake Ball and two by Chris Jordan - interrupted India's chase.
Batting first, England posted a huge score before Pandya and Dhoni pinned them back and the hosts finished on 198-9 after their 20 overs.
Chinaman bowler Kuldeep Yadav was dropped raising a few eyebrows as he had taken five wickets in the first game.
Roy, though, didn't stop playing his shots as he hit a big six to take England past the 100 mark in the 10th over but in the same over, Roy fell for 67, giving Deepak Chahar his first worldwide wicket on his debut. Record century-maker on Tuesday, Aaron Finch, went for just 16 while fellow opener Darcy Short struggled to 28 off a glacial 34 balls.
"It's just that, I don't think I've changed much technically and obviously being away from the game and not playing much, gives me time to train and gives me time to work a lot on my fitness". Kaul (2/35) bowled a quicker, fuller delivery and Buttler missed as he was bowled.
In the next over, Buttler took Umesh Yadav (1/48) for two back-to-back fours to set the tone for his team before Roy turned on the heat. Dhawan clung on in the deep to dismiss Eoin Morgan with a magnificent leaping effort on the boundary.
Stepping out to bat, India were troubled right from the word go. Dhoni completed the catch this time around.
The hero of the match for England was Alex Hales.
The host's team England lost 5 wickets for chasing 21 runs with only 14 balls left.