Rangana Herath claimed his maiden Test hat trick as 21 wickets tumbled on a frantic second day with host Sri Lanka closing in on a series-clinching victory against Australia in the second Test here Friday. The dramatic day began with Australia resuming on 54-2 before being 106 all out to concede a 175-run first innings lead. Three Sri Lankan batsmen were also dismissed in the 11-wicket morning session but the host recovered to post 237 all out, setting Australia a daunting 413-run victory target to stay alive in the three-Test series. Australia's struggle against spin was obvious in the second innings as well as the tourists slumped to 25-3 at stumps. David Warner was batting on 22 at the break, while skipper Steve Smith was on one after coming out to bat for the second time in the day with Australia staring at an embarrassing defeat inside three days. Herath had tormented Australia in the first Test at Pallekele, exposing its vulnerability against spin bowling and claiming nine wickets in Sri Lanka's 106-run victory. The 38-year-old left-arm spinner haunted it again Friday, castling Smith for five runs with the first delivery of his third over. He ripped the heart out of Australia's batting in his seventh over, getting Adam Voges caught at extra cover with his fourth delivery and trapping Peter Nevill plumb in front with an arm ball. He struck Mitchell Starc's pad with his next delivery and home captain Angelo Mathews successfully reviewed the original not-out decision as Herath (4-35) became only the second Sri Lankan cricketer to get a Test hat trick. Former paceman Nuwan Zoysa was the first Sri Lankan to achieve the feat, against Zimbabwe in a 1999 match in Harare. Off-spinner Dilruwan Perera polished off the tail to finish with 4-29 as Australia folded inside 34 overs. Sri Lanka got off to a shaky start and, for the second time in the match, Kusal Mendis walked out to bat with his team reeling at nine for two. The architect of Sri Lanka's Pallekele win and its top-scorer in the first innings, however, made only seven runs before Starc (6-50) sent him back. The left-arm paceman claimed a match haul of 11 wickets but a half-century from Dilruwan Perera (64) and handy knocks from Kusal Perera (35), Mathews (47) and Dhananjaya de Silva (34) extended Sri Lanka's lead. Hope replaces Chandrika West Indies opening batsman Rajendra Chandrika has paid the price for his lack of runs in the first two Tests against India and been dropped for the third Test that starts in St. Lucia next Tuesday. Chandrika has been replaced by Shai Hope in the 14-man squad, selectors said Thursday. India leads the four-Test series 1-0, but West Indies took enormous heart from drawing the second Test, after appearing doomed for defeat until a stellar final-day batting effort saved the match. The Windies have made no other changes in the 14-man squad from the second Test.