CHICAGO (AP) Aaron Ekblad had a big goal for the Florida Panthers, and then it was gone. Same for Vladimir Tarasenko in St. Louis last week. Andrew Shaw of the Chicago Blackhawks and Derick Brassard of the New York Rangers got to keep their clutch scores.
The breakout star of the first round of the NHL playoffs is the coach's challenge, and it seems as if no one is quite sure how they feel about its prominence. There were two more on Sunday, including an offside ruling that negated Ekblad's goal in the second period of Florida's 4-3 overtime loss at the New York Islanders.
''The rule is there, it's in place and you have to do as good a job as possible as a staff and as a group to execute within the rule,'' Philadelphia coach Dave Hakstol said. ''We're seeing how important and how much of an impact it's had on a couple of games.''
The NHL approved the coach's challenge system last summer, and it was used 266 times in the regular season, with 68 plays overturned. The system was mostly praised, save for the occasional display from a coach or player upset when a reversal went against their team.
The addition of blue-line cameras for the playoffs has created additional scrutiny and set the table for more changes before next season. Heading into Monday's action, there had been eight challenges in the playoffs, with three plays overturned - each of them wiping out a goal for offside.
Asked if the coach's challenge is good for the game, St. Louis coach Ken Hitchcock responded: ''I don't know. That's probably for summertime conversation.''
A pair of challenges went against the Blues in the third period of their 3-2 loss to the Chicago Blackhawks in Game 2 of their series. Tarasenko's tiebreaking goal was erased by a razor-thin offside ruling on Jori Lehtera based on video from the blue-line cameras.
There was a video review of Shaw's tiebreaking goal before Hitchcock unsuccessfully challenged the play, arguing goaltender Brian Elliott had been pushed into the net on the score.
The review and challenge sequence caught the attention of several players.
''They get the OK from Toronto before the challenge and then we challenge and then there's another seven or eight minutes,'' Blues center Paul Stastny said. ''I think the game's changed so much, I guess that's the only downside to the challenges. You don't mind them for certain reasons, but you want to get an answer in 30 seconds, a minute, two minutes, quick; almost like a quick timeout basically.''
Henrik Zetterberg's second-period goal in Detroit's 2-0 victory over Tampa Bay on Sunday night was reviewed to determine if the center used a kicking motion to score. Then Lightning coach Jon Cooper tried an unsuccessful challenge for goaltender interference.
''The only bad thing is, it takes time, especially yesterday when they reviewed the kicking motion, then it went straight into the coach's challenge,'' Zetterberg said. ''But I think overall, it has been (a) good thing (this) year. If they could speed it up somehow, it would probably be better.''
The challenge system and blue-line cameras also have pointed more attention toward one of the most unheralded positions on NHL coaching staffs - video coach.
Florida almost had a 3-0 lead in the second period against New York, but Ekblad's first career playoff goal was thrown out when video coach Matt Bertani got Islanders coach Jack Capuano to challenge the play and video showed Florida was offside when it entered the zone.
''That was the turning point,'' Capuano said. ''Down by two is a lot different than down by three.''
Blackhawks defenseman Duncan Keith praised video coach Matt Meacham for the call on Tarasenko's goal in Game 2. Hard to imagine a pair of video coaches drawing public praise during the NHL playoffs before, much less a single round.
The positive experience with challenges in the playoffs is quite a turnaround for Chicago coach Joel Quenneville, who threw his arms in the air and cut short a postgame news conference when asked about a disallowed goal against San Jose in February.
Quenneville almost didn't make his challenge in time against St. Louis, raising the question of whether the NHL might need to go to a more formal way of notifying the referees in those cases - such as the red flag in the NFL. Quenneville was game for whatever.
''I was almost ready to jump on the ice'' in Game 2, Quenneville said.
AP Sports Writers Stephen Whyno and Vin A. Cherwoo and Hockey Writer Larry Lage contributed to this report.
Jay Cohen can be reached at http://www.twitter.com/jcohenap