Ones to watch: Dries Mertens - Belgium
Age: 31Club: NapoliCaps: 70
One of the oldest players in the Belgium squad, Dries Mertens is an explosive forward who comes into the World Cup as a starter for the talented Red Devils.
For opposition defenders, Mertens represents a very different challenge to other forwards such as Romelu Lukaku or Christian Benteke.
He's fast, works the channels exceptionally well and can beat defenders one-on-one—and over the last two years has been a reliable, goalscorer in Serie A with Napoli.
Mertens hit 28 league goals in 2016/17 and followed that up with 18 this past season, despite ending the campaign with just one in his last 11.
A former wide forward who only emerged as a central option in 2016, Mertens has been a regular starter under Roberto Martinez—though their array of attacking options means he's often either subbed off or enters as a sub himself, rarely completing the full 90 minutes.
He's likely to be deployed as one of two support players—the other being Eden Hazard—to a striker, but has the versatility to help the team switch systems when needed.
Mertens is still perhaps waiting for his big moment in international colours, but could certainly come up with the goals to fire his team toward the latter stages.