Coach's Challenge: OTT @ FLA - 13:57 of Third Period

At 13:57 of the third period in the Senators/Panthers game, Ottawa requested a Coach's Challenge to review whether Florida was off-side prior to Jonathan Marchessault's goal.
After reviewing all available replays and consulting with the linesmen, NHL Hockey Operations staff determined that the Panthers entered the attacking zone legally prior to the goal.

Therefore the original call stands - good goal Florida Panthers.
Since the Coach's Challenge did not result in the original call being overturned, the Ottawa Senators forfeit their time-out.