DEFENSIVE lapses proved costly for the Bundanoon Highlanders on Saturday.

The Highlanders had a tough day against last season's second division premier Narellan White.

In front of its home crowd, Narellan recorded a 40-26 victory.

Bundanoon coach Brian Martin said conditions were tough,with the temperature reaching 30 degrees.

Martin said his team worked hard, but was made to pay for costly misses in defence.

"Narellan has a pretty big pack which I thought we handled pretty well, but they were hard to stop close to our (try) line," he said.

"When you concede 40 points, there is something wrong with your defence and it's something we will work on."

There were some positive signs for the Highlanders on Saturday.

Teenager Max Hanrahan bagged two tries and Jarrod Woodgate had another strong game in the forwards.

But the defeat was compounded by a serious knee injury to playmaker Hayden Menzies.