PALLEKELE (AFP) - Mitchell Johnson grabbed a career-best 6-31 and Shane Watson smashed a brisk 69 to guide Australia to a seven-wicket win over Sri Lanka in the first one-dayer on Wednesday. Opener Watson cracked six sixes and five fours in his 51-ball knock as Australia achieved a 192-run target with more than 11 overs to spare for a 1-0 lead in the five-match series. Left-arm fast bowler Johnson played a key role in restricting Sri Lanka to a modest total, marking his 100th one-day international with disciplined bowling to bag his third haul of five or more wickets. Watson then kept pressure on Sri Lanka with an exciting strokeplay, reaching his 24th half-century in one-dayers with a six off unorthodox spinner Ajantha Mendis. He dominated a 59-run stand for the opening wicket with Brad Haddin (12) before falling in the 12th over, but had put his team in a strong position at that stage. He also completed 4,000 runs in one-dayers during his knock. Skipper Michael Clarke (53 not out) then added 101 for the third wicket with Ricky Ponting (53) to steer his team home. Australian paceman Brett Lee earlier became the seventh bowler to take 350 wickets in one-dayers when he dismissed Nuwan Kulasekara (34) for his lone victim of the innings. Sri Lanka were struggling at 117-7 following Johnson's four-wicket burst in his opening spell before lower-order batsmen Suraj Randiv, who hit one six and four fours in his 41, and Kulasekara put on 60 runs for the eighth wicket. Johnson ended Sri Lanka's resistance when he had Randiv -- the home side's highest scorer -- caught in the deep and then bowled Ajantha Mendis in his ninth over. Sri Lanka got off to a solid start after winning the toss when Upul Tharanga (34) and skipper Tillakaratne Dilshan (29) put on 54 for the opening wicket before Australia struck back. Tharanga, returning to the side after serving a three-month drugs ban, looked in good touch as he fluently drove Lee for two successive fours in the opening over. Sri Lanka's slide began with the dismissal of Tharanga, who was bowled by left-arm spinner Xavier Doherty while attempting to cut after hitting seven fours in his 28-ball knock. Johnson struck in his first over when he had Mahela Jayawardene caught behind and then had Kumar Sangakkara caught in the covers. He also accounted for Jeevan Mendis and Angelo Mathews in his opening seven-over spell. "This was not a 190 wicket, we did not bat well," said Sri Lanka captain Dilshan. "It was a good toss to win but our shot selection was not good." Australian captain Clarke added: "It is important that I lead from the front. It's great to have Ponting at number three with all that experience at the other end." SCOREBOARD SRI LANKA: U Tharanga b Doherty 34 T Dilshan c Bollinger b D. Hussey 29 K Sangakkara c Smith b Johnson 16 M Jayawardene c Haddin b Johnson 3 D Chandimal c Clarke b Bollinger 12 A Mathews c Watson b Johnson 15 J Mendis b Johnson 2 S Randiv c Doherty b Johnson 41 N Kulasekara c M. Hussey b Lee 34 A Mendis b Johnson 0 S Lakmal not out 0 EXTRAS: (lb3, w2) 5 TOTAL: (for all out; 41.1 overs) 191 FOW: 1-54, 2-76, 3-80, 4-89, 5-101, 6-112, 7-117, 8-177, 9-177, 10-191 BOWLING: brett Lee 7.1-0-33-1, Bollinger 7-1-34-1, Watson 2-0-12-0, Doherty 10-1-48-1, D Hussey 2-0-12-1, Johnson 10-1-31-6, Smith 3-0-18-0 AUSTRALIA: S Watson c Jayawardene b Randiv 69 B Haddin b A Mendis 12 R Ponting b Randiv 53 M Clarke not out 53 M Hussey not out 2 EXTRAS: (lb1, w2) 3 TOTAL: (for 3 wkts; 38.1 overs) 192 FOW: 1-59, 2-81, 3-182 BOWLING: Kulasekara 5-1-21-0, Lakmal 5-0-39-0, A. Mendis 6-0-32-1, Randiv 8.1-0-44-2, J. Mendis 9-0-37-0, Dilshan 5-1-18-0