The verdict is in: It's Matt Murray.
"I'm not going to elaborate on the decision," Sullivan said, according to TSN's Frank Seravalli.
Fleury was pulled from Game 3 on Wednesday after Ottawa blitzed Pittsburgh for four goals on only nine shots in the first period. Murray stopped 19-of-20 shots in relief, and Fleury will resume his backup duties behind the 22-year-old.
Friday will be Murray's first start of the playoffs. He was hurt in warmups ahead of Game 1 in the first round, with Fleury taking over and leading the Penguins to their nine spring wins.
Last season, Murray took over for Fleury late in the season, winning 15 games in the playoffs as Pittsburgh won its second Stanley Cup in the Sidney Crosby era.
Ottawa leads the Eastern Conference Final 2-1.