The Worcestershire off-spinner´s treble saw him snare Dean Elgar and Kagiso Rabada with the aid of two slip catches by Ben Stokes at the end of his 16th over, before he had Morne Morkel lbw on review with the first ball of his next.
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Morkel´s dismissal ended the match after lunch on the fifth day, with England winning by 239 runs to go 2-1 up in this four-Test series.
It was the first time in more than a hundred years that a Test had ended with a hat-trick, with Australia off-spinner Hugh Trumble the last bowler to finish a match at this level in similar fashion, against England at Melbourne in 1902.
Ali´s hat-trick was also the first in The Oval´s 100-Test history — which dates back to 1880 — and the first by an England spinner since Tom Goddard´s against South Africa at Johannesburg in 1938.
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In all there have been 14 England Test hat-tricks, with paceman Stuart Broad — a current team-mate of Ali — having twice performed the feat.
England Test hat-tricks (season, player, opposition, venue):
1882/83 Billy Bates v AUS Melbourne
1891/92 Johnny Briggs v AUS Sydney
1895/96 George Lohmann v RSA Port Elizabeth
1899 Jack Hearne v AUS Headingley
1929/30 Maurice Allom v NZL Christchurch
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1938/39 Tom Goddard v RSA Johannesburg
1957 Peter Loader v WIS Headingley
1995 Dominic Cork v WIS Old Trafford
1998/99 Darren Gough v AUS Sydney
2003/04 Matthew Hoggard v WIS Barbados
2007/08 Ryan Sidebottom v NZL Hamilton
2011 Stuart Broad v IND Trent Bridge
2014 Stuart Broad v SRI Headingley
2017 Moeen Ali v RSA The Oval
Match-ending Test hat-tricks (season, player, country, opposition, venue):
1895/96 George Lohmann ENG v RSA Port Elizabeth
1901/02 Hugh Trumble AUS v ENG Melbourne
2017 Moeen Ali ENG v RSA The Oval