Efrem Lukatsky/Associated Press

Croatia booked their ticket for the next round of the 2018 FIFA World Cup on Sunday, beating Denmark on penalties in a round-of-16 clash.

The 1998 third-placed finishers grabbed their first win in a knockout match in a major tournament since that historic run and will meet hosts Russia in the next round.

Mathias Jorgensen and Mario Mandzukic got the match off to a fine start with two early goals, but things regressed rapidly after that. Luka Modric missed a penalty in extra time but did return to score his second attempt in the shootout.

Danijel Subasic and Kasper Schmeichel both flashed their talent, as they saved the penalties of Christian Eriksen, Milan Badelj, Lasse Schone, Josip Pivaric and Nicolai Jorgensen.

Here are the key takeaways from the match.

Modric Can't Let Poor Outing Rattle His Confidence

Real Madrid star Modric had arguably been the tournament's top performer in the group stages, but he ran into a phenomenal Thomas Delaney on Sunday and was unable to leave his mark on the contest.

He sent in a handful of nice passes―including the one that led to the late penalty―but was visibly nervous in extra time, and things got worse after his penalty miss. By the time he stepped to the plate again in the shootout, the 32-year-old was almost shaking, and he had another poor effort that was nearly saved once more.

None of this will matter for the Croats, who finally grabbed the knockout win they so desperately craved, but it's pivotal Modric doesn't let this one bad outing linger or shake his confidence. He is Croatia's most important man in midfield, and they'll need him at his best to unlock Russia's solid defence.

Schmeichel's Heroics Undone by Teammates' Poor Penalties

When FIFA announces its team of the tournament and award for the top goalkeeper, Schmeichel should at the very least get an honourable mention, even if his team didn't win a knockout match.

He was phenomenal against Peru, a match the Danes easily could have lost, and continued his stellar play in the group stages. Against Croatia, he didn't have to make a ton of key saves, but by saving three penalties in total, he once again came through.

Denmark's other top stars―most notably Christian Eriksen and Pione Sisto―were far from their best in Russia, and they let their star stopper down. On Sunday, the former set the tone in the shootout by missing their first attempt, and the latter didn't even get the chance to take a penalty after he was dropped from the starting XI.

Croatia's Versatility a Lesson for Other Contenders

While much of the focus has been on Croatia's sublime central midfield options, the side is one of the few top teams in the tournament that has shown success with their tactical versatility.

Not everything has to go through Modric and Ivan Rakitic―speedy wingers Ivan Perisic and Ante Rebic are perfectly capable of creating danger on their own, and thanks to the team's physicality, they can score the ugly goals as well, as evidenced by Mandzukic's strike.

Denmark did a great job locking up the Croatian midfield Sunday, and the team adapted and found other ways to deal with the threats and create danger. It didn't lead to any more goals, but at least they came close―something Spain never did after Russia's equaliser earlier in the day.

La Roja―and defending champions Germany―came undone because they never figured out a Plan B, and that's a problem Croatia don't appear to have. It's a huge weapon moving forward, and it should lead to a better showing against the hosts.

What's Next?

The round of 16 continues Monday, as Brazil face off with Mexico and Belgium take on Japan.