England 373 for 3 (Buttler 110*, Roy 87, Morgan 71*, Bairstow 51) beat Pakistan 361 for 7 (Fakhar 138, Babar 51, Asif 51) by 12 runs
Southampton: Jos Buttler scored England's second-fastest ODI century to fire them to a 12-run victory over Pakistan in the second match of the series at Southampton.
Buttler owns the record for England's quickest ton in the 50-over format having hitting a 46-ball hundred against the same opposition in 2015.
He came close to besting that in another devastating performance, which encompassed six fours and nine maximums, as Buttler put on a pivotal partnership of 162 for the fifth-wicket with captain Eoin Morgan (71 not out).
Buttler finished unbeaten on 110 as England closed on 373-3, a target that proved too big for Pakistan even with Fakhar Zaman's superb 138.
The tourists finished with 361-7 and fall 1-0 behind in the series after the opener was rained off earlier this week.
Jason Roy (87) and Jonny Bairstow (51) provided England with a great platform to work with, though their 115-run opening stand would have been curtailed had Bairstow not survived an lbw review.
Bairstow pulled to Fakhar, who made a superb catch at the square leg fence, the ball after reaching his 50 and Roy looped to mid-on after a rain delay checked England's momentum.
Joe Root went to Yasir Shah for 40 but Morgan and Buttler, who brought up his century with a booming shot over long-off, produced a scintillating finish to the innings, the final five overs going for 74.
Pakistan's innings never hit the same heights but 92 runs were on the board by the time Imam-ul-Haq (35) was caught and bowled by Moeen Ali.
Fakhar provided their main threat with 12 fours to go with four maximums, but he was caught behind by Buttler chasing a wide delivery and Pakistan's hopes were dented further when Babar Azam (51) followed five balls later.
Asif Ali (51) kept Pakistan in the hunt with stands of 41 and 49 with Haris Sohail and Sarfaraz Ahmed, but his departure in the 46th over to David Willey - who had dropped him earlier - sparked an excellent spell of death bowling from England.
The last three overs featured two wickets and no boundaries, with Morgan and Buttler's late firepower ultimately proving the difference.