According to Elliotte Friedman, Max Pacioretty is expected to be out for approximately six weeks (reportedly a fractured foot), while the Golden Knights are waiting for further information on Mark Stone. The team's Twitter account later clarified that Pacioretty is out week-to-week, while Stone is currently day-to-day and currently being evaluated. Pacioretty and Stone were Vegas's two leading scorers last season, so these injuries could be a major blow early on.
Thinking on the Stone injury (because he's on more than one of my rosters), this appears to be something more concerning than just cramps. It may be a core muscle injury, which can make it incredibly difficult to move around, having experienced this myself. Stone could be out multiple weeks as well, especially if surgery is required. But it sounds like the delay is about getting a second opinion that could avoid a lengthy absence.
I'd expect Evgenii Dadonov to move up into the top 6 for sure, as he filled in for Stone when he left Thursday's game. If Dadonov is available in your league, I'd give him a look. He's featured in this week's Looking Ahead. Nolan Patrick and Peyton Krebs are also possibilities for increased roles. As well, the other scoring line of William Karlsson, Jonathan Marchessault, and Reilly Smith will likely be leaned on as the top line. We really won't know how things shake out for a few days, though, as Vegas' next game is on Wednesday.
Dobber has also updated the Fantasy Guide to account for the Pacioretty/Stone injuries, so be sure to download.
The Lightning were able to pull off a 2-1 overtime victory over Washington, but it came at a cost. Nikita Kucherov left the game in the third period after bumping into (or trying to avoid?) Garnet Hathaway. He appeared to be in a lot of discomfort, so hopefully this isn't something serious. Jon Cooper did not have an update after the game and said not to "hit the panic button", so we'll have to wait and see if this is anything serious.