On his last day as a teenager — and then again on his first day as a 20-year-old — world champion D Gukesh was reminded that there is still some growing up for him to do. On Thursday, a day before he turned 20, the world champion from India picked up a fight on the board against world no 1 Magnus Carlsen. And lost. “Gukesh sometimes plays a bit too ambitiously. He wanted to prove a serious advantage today, which I’m not sure there was,” Carlsen said about his quarry later. “Eventually, he played himself into some trouble. And I took over more and more.” Even though Friday was a rest day at the tournament, Gukesh turned 20 in the company of fellow grandmasters, including world championship challenger Javokhir Sindarov and Carlsen. The players spent three hours on sailboats racing against each other at Oslofjord in the annual Norway Chess games, where at least twice, impromptu chorus of happy birthday rang out for a grinning Gukesh. But just before the players were to get on …