Naomi Osaka exited the Qatar Open with a narrow quarterfinal loss to fellow former world No. 1 Karolina Pliskova on Thursday. Pliskova crept into the semis with a 7-6(6) 7-6(5) victory over the four-time major winner from Japan after both sets went to tiebreaks. Osaka, who returned from a maternity break at the Brisbane Open in January, was playing in the last eight at a tournament for the first time in nearly two years. Looking to avenge the first loss of her comeback to Pliskova in Brisbane, Osaka made a strong start by going up 5-3 in the first set in Doha. The Czech player got back on leve…