Former Republic of Ireland and Manchester City defender Terry Phelan has said that mental strength and concentration will be the decisive factors as the FIFA World Cup 2026 enters its Round of 16 knockout stage, where a single lapse can end a nation's campaign.

No Margin for Error

Phelan, speaking as part of the expert panel for Zee5's FIFA World Cup 2026 coverage, was emphatic that the dynamics of the tournament shift dramatically once the group stage ends. “It’s a do-or-die situation now. The top players have to show that winning mentality individually and collectively because there’s no margin for mistakes. A lapse of concentration can cost you,” he said.

The knockout rounds reward teams that can absorb pressure and punish those that switch off, even briefly. Phelan underlined that defensive discipline is no longer optional at this stage. “Concentration is everything in knockout football. It only takes a second for the ball to end up in the back of the net, so defenders have to stay switched on from the first whistle to the last,” he added.

France Flying Under the Radar

Among the contenders, Phelan singled out France as the team most likely to surprise. While public attention has centred on England, Spain, Portugal, and Argentina, Phelan argued that France’s quieter build-up could be an advantage. “France have gone under the radar. Everyone is talking about England, Spain, Portugal and Argentina, but France have been doing things the right way. They could surprise a lot of people,” he said.

Golden Boot Race Heats Up

The knockout phase has sharpened the race for the Golden Boot, with Lionel Messi, Kylian Mbappé, Harry Kane, Erling Haaland, and Cristiano Ronaldo all in contention as they attempt to carry their nations into the quarter-finals. “This is why you pay the big money for top strikers. They keep delivering on the biggest stage, and it’s wonderful to see them competing for the Golden Boot,” Phelan said.

Portugal vs Spain and the Messi-Ronaldo Saga

One of the marquee Round of 16 fixtures pits Portugal against Spain, with Cristiano Ronaldo still chasing a maiden FIFA World Cup title. Meanwhile, Lionel Messi continues to lead Argentina’s defence of the title they won in 2022. Phelan urged fans to savour the enduring rivalry between the two icons. “Let’s enjoy them while we can. The debate will always continue, but if one of them lifts the World Cup, it’ll only add another chapter to their incredible rivalry,” he said.

Argentina the Team to Beat

Despite the field of strong contenders, Phelan backed defending champions Argentina as the favourites to go all the way. “Argentina look dominant. They look like gladiators, and they mean business. With Lionel Messi leading them, I think they’re the team everybody has to beat,” he said.

With quarter-final berths at stake and the tournament entering its most intense phase, the FIFA World Cup 2026 Round of 16 is set to deliver high-pressure football that could define the legacies of some of the game’s greatest players.