The “Big Fish” made a big splash in his NBA Summer League debut.

Former Hawaii basketball center Isaac Johnson made the most of his 20 minutes off the bench for the Philadelphia 76ers on the first day of competition at UNLV’s Cox Pavilion on Thursday, scoring 20 points on 6-for-10 shooting in a 101-93 win over the Detroit Pistons.

Johnson, an All-Big West first-teamer from American Fork, Utah, who led the Rainbow Warriors in scoring en route to an NCAA Tournament appearance in his lone season in Manoa, quickly made his versatile game translate to the showcase that is NBA summer ball. The 7-footer, a free agent who was invited to the summer roster, canned four of six 3-pointers in leading the Sixers with a plus-13 plus-minus rating.

He was surpassed in the scoring column only by Dante Maddox Jr. (21). Johnson contributed two rebounds and an assist.

Johnson first entered in the second quarter and three minutes later hit a triple on an assist from first-round draft pick Labaron Philon. In the fourth quarter, he hit a 7-foot floater and stepped out for his fourth and final 3 with 2:01 left, absorbing contact from an oncoming Ugonna Onyenso. Johnson flashed “3” in front of his face as he hit the court, got up and sank the free throw for the four-point play.

The Sixers resume summer ball against the Indiana Pacers at 11:30 a.m. Hawaii time Saturday.

Brian McInnis covers the state’s sports scene for Spectrum News Hawaii. He can be reached at brian.mcinnis@charter.com.