The slick Otago Boys' backline scored six tries to beat John McGlashan College 39-5 in Dunedin.
Lawrence (16) is a top Otago sprinter on the track and represented New Zealand at the Oceania championship in Sydney in March.
He used his speed to wrong-foot the John McGlashan defence and was also a strong defender.
The Otago Boys' backline was efficiently directed by halfback Kurt Hammer.
He combined well with his first five-eighth, Lance Taylor, who scored two tries.
Michael Collins was solid in the midfield and fullback Liam Edwards scored 14 points to reach a century after just four games in the Highlanders competition.
The John McGlashan pack had the better of Otago Boys' in the scrum and the clean-out and was able to slow the ball down in the ruck.
The key players for McGlashan were the loose trio of Braydon Pennycook, Nathan Hull and Nick Ryder.
Southland Boys' High School put its foot on the accelerator with a commanding 81-7 win over South Otago High School in Invercargill.
Southland Boys' and Otago Boys' are two of the four unbeaten teams after four rounds of the competition.
The other unbeaten teams are King's High School, which beat Waitaki Boys' High School 25-10 in the midweek game, and Gore High School.
Gore scored 10 tries when it beat Kavanagh College 64-0 at home.
Aaron Shirley scored two tries.
Gore has a strong pack and kept hold of the ball for the first 20 minutes to score four tries and lead 22-0.
Two of the best players in the pack were props James Matheson and Ben Crawford, who were efficient at the pick and go, while first five-eighth Hamish Cook helped the forwards by punting accurately for territory.
Hayden Stephen had a strong game on the wing.
Kavanagh College was let down by poor tackling around the fringes and in the backs, but loose forwards Andrew Toomey and Chris Bourne were strong defenders.
The best attacker was first five-eighth Rhys Johnson.
Dunstan High School gained is first win of the season when it beat Central Southland College 12-0, and St Kevin's College broke its duck when it downed Verdon College 14-5.
The big game this Saturday is between Otago Boys' and Southland Boys' at Littlebourne at 2.30pm.
Gore plays unbeaten Kings High School in another crunch game in Dunedin.
Points after four games: Otago Boys' 20, King's 20, Southland Boys' 19, Gore 18, Waitaki Boys' 9, John McGlashan 9, Dunstan 6, St Kevin's 4, Kavanagh 4, South Otago 1, Central Southland 0.
