GALLE: Thilan Thushara and Muttiah Muralitharan claimed four wickets each as Sri Lanka gained a 153-run lead at lunch Friday in the first cricket Test against New Zealand.

The illness-hit Black Caps, replying to the home team's first innings total of 452, were bowled out for 299 in the morning session of the fourth day at the Galle International Stadium.

Sri Lanka went to lunch at 76-1 in their second knock, an overall lead of 229 runs with nine wickets in hand.

Tillakaratne Dilshan was unbeaten on a typically aggressive 46 off 31 balls and skipper Kumar Sangakkara was on 20 after Tharanga Paranavitana was snapped up in the slips off Iain O'Brien for five.

The Kiwis woke up on Friday with the news that batsman Jesse Ryder and wicket-keeper Brendon McCullum had been laid low by a stomach bug and may not take further part in the Test.

"They are very sick and I am not sure if, and at what stage, they will take part in this Test," Black Caps manager David Currie told reporters.

The immediate concern for the tourists was finding a reserve wicket-keeper for the rest of the Test since Ryder had been nominated to don the gloves if McCullum got injured.

"There was no one else in the playing XI who could keep wicket and we requested the Sri Lankans if we could call up reserve wicket-keeper Reece Young as a special case," said Currie.

"The Sri Lankans kindly agreed to our request and we are very grateful to them."

Rules do not allow anyone outside the playing XI from keeping wicket.

Currie said five other players -- Jacob Oram, Jeetan Patel, captain Daniel Vettori, Tim McIntosh and Chris Martin -- had suffered stomach bugs since the Test started on Tuesday.

New Zealand, who resumed on the overnight score of 281-8, added 18 runs before they were all out 40 minutes after the start of the day's play.

Muralitharan, Test cricket's leading bowler, had O'Brien caught behind to claim his 100th wicket at Galle and take his overall record tally to 774 wickets.

Thushara then bowled Vettori in his first over, but not before the New Zealand captain had contributed a defiant 42.