ZAGREB, Croatia (AP) — Croatia took a decisive step toward World Cup qualification on Thursday, overwhelming Greece for a 4-1 victory in the first leg of their playoff.

Captain Luka Modric, whose recent form for Real Madrid had been criticized in Spain, opened the scoring from the penalty spot in the 13th minute - before leaping into the air in celebration.

Italian referee Gianluca Rocchi awarded the penalty after Greece goalkeeper Orestis Karnezis failed to control the ball and fouled Nikola Kalinic with a poorly judged clearance.

Kalinic added another goal six minutes later, flicking in a cross from Ivan Strinic with the side of his foot.

Greece struggled to regain composure and rarely attacked, but Sokratis Papastathopoulos briefly silenced the home crowd, sending a header over keeper Danijel Subasic and into the net.

However, relief for the visitors was short lived. Ivan Perisic headed in a cross from Sime Vrsaljko in the 33nd minute as the Croats dominated both wings.

The fourth goal came four minutes after the break from Andrej Kramaric, swooping in after another Greek error, by Kostas Stafylidis.

As fans and players celebrated at Zagreb's Maksimir Stadium, Croatia coach Zlatko Dalic highlighted the second leg on Sunday.

"We had a tremendous game. I've thanked the players and the fans who made us feel like we had an extra man on the pitch," Dalic said. "But it's not over. This was the first game.

"Our aim tonight was to pressure Greece down the wings, and that worked. We had a lapse in concentration and conceded a goal, but I can't really complain."

Over 90 minutes, the Croats dominated possession and had nine shots on goal compared to Greece's three.

"It was a very difficult night for us ... We have never made so many mistakes in one game," Papastathopoulos said. "Of course Croatia has the upper hand now. They have a 90 percent chance of going through."

Greece coach Michael Skibbe said his team failed to fully recover from the first goal.

"If you help your opponents score the first and the fourth goal then it's very difficult to be competitive," he said. "Of course we are very unhappy right now. We will be a better team in the next match."

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Derek Gatopoulos contributed from Athens, Greece