Darius Morris steps up for Lakers

The Lakers praised Darius Morris for providing a modest boost in his NBA debut Wednesday.

Two days later, the team needed much more from the rookie point guard.

Morris went from bit player to major supporting role Friday after the Lakers learned backup guard Steve Blake would be sidelined three to four weeks because of a fracture of the cartilage that connects the rib to the sternum.

Blake said he started feeling soreness in the area near his rib after Tuesday’s game against Phoenix. He aggravated the injury Wednesday against Utah when he awkwardly twisted his body late in the third quarter.

Blake’s absence will result in a significantly increased role for Morris, the former Michigan and Los Angeles Windward High standout whose NBA career consisted of 13 minutes before Friday.

“I’m just really looking forward to maximizing my opportunity,” Morris said before the Lakers’ game against the Cleveland Cavaliers at Staples Center.

He entered with 5 minutes 20 seconds left in the first quarter and was actively involved in the Lakers’ next three possessions, making a three-pointer and collecting two assists.

My three sons

Lakers radio color commentator Mychal Thompson was hoping to call a second game involving one of his sons, but Cleveland deactivated rookie Mychel Thompson earlier this week to make room on their roster for Semih Erden.

It had already been a big week for the Thompson family inside Staples Center. Klay Thompson, Mychal’s middle son, scored a career-high 14 points for Golden State on Jan. 6 against the Lakers.

Mychal said he would be more edgy watching Mychel play because Klay’s status was assured as a first-round draft pick; Mychel made the Cavaliers’ roster as an undrafted forward out of Pepperdine.

“Mychel is a guy who walked on, basically,” Mychal said of his oldest son, who has played in one game. “He’s on the team, but his position is a little more tenuous because when you are the 13th or 14th or 15th man on a team, you just hope that you can do positive things to stick around, so I’m real nervous that he can continue to impress his coaches to want to keep him around.”

Mychal’s youngest son, Trayce, is a minor league outfielder in the Chicago White Sox organization.

In the zone?

The Lakers unveiled a zone defense for the first time under Coach Mike Brown against Utah on Wednesday, using it for a brief stretch in the second half when their reserves were on the floor.

Brown said his coaching staff worked extensively on zone schemes during the lockout but didn’t think he would have time to effectively teach it during a condensed season.

“Hopefully,” Brown said, “it’s Plan D.”

ben.bolch@latimes.com