Cricket - Starc, Lyon strike before lunch to leave Sri Lanka reeling

COLOMBO (Reuters) - Fast bowler Mitchell Starc combined with off-spinner Nathan Lyon to dismiss half of Sri Lanka's batting line-up after the hosts won the toss and opted to bat in the third and final test against Australia on Saturday.

Left-arm paceman Starc, the most successful bowler in the series, was at his devastating best and picked up three wickets, taking his tally for the series to 20.

Captain Steve Smith introduced Lyon in the sixth over with the pitch at the Sinhalese Sports Club Ground already providing some assistance to the spinners and was rewarded with two wickets.

At lunch, Sri Lanka, who have an unassailable 2-0 lead in the three-match series, were 55 for the loss of five wickets with Dhananjaya de Silva (23) and Dinesh Chandimal (seven) at the crease.

Starc, bowling with pace and accuracy, sent back Sri Lanka's faltering opening batsmen, with Kaushal Silva falling for a duck and Dimuth Karunaratne (seven) getting out to the same bowler for all five times in the series.

Kusal Perera (16) hit three boundaries before edging Lyon to Smith at slip while the off-spinner also picked up Sri Lanka captain Angelo Mathews' wicket, the batsman top-edging his sweep shot to deep square leg.

Starc returned for another spell to dismiss in-form Kusal Mendis for one, Smith completing another smart catch behind the wickets.

Lyon thought he had his third when De Silva was given out off a bat-pad catch but the batsman managed to overturn the decision on review.

De Silva and Chandimal added 29 runs for the unbroken sixth wicket and Sri Lanka's hopes of building a sizeable first-innings total will rest on their shoulders.

Paceman Suranga Lakmal recovered from a hamstring injury to replace Vishwa Fernando in the only change for the hosts from the team that beat Australia by 229 runs in Galle.

Australia, whose top ranking in the format is at stake, dropped opening batsman Joe Burns and number three Usman Khawaja from a side that have struggled against the hosts' spinners.

Left-handed batsman Shaun Marsh and all-rounder Moises Henriques, who last played a test match in March 2013, were drafted in.

(Reporting by Sudipto Ganguly in Mumbai; editing by Peter Rutherford)