We’re probably not quite at the stage of “biggest game in United States men’s national team history,” but it’s getting close. The U.S. has been in the final 16 of World Cups with some regularity for a generation, and only once in that era have they made it past that stage. There’s another chance Monday.The U.S. is basically in a coin flip with Belgium, at least according to the odds.For the non-American audience, Spain-Portugal is a mouthwatering matchup earlier in the day.Here’s a look at both matches and some picks from our betting staff.Spain-PortugalTime: 3 p.m. ETTV: Fox (English), Telemundo (Spanish)Venue: AT&T Stadium, Arlington, TexasThis is the undercard to Americans, but it’s a big-time matchup in multiple ways. It’s two European powers meeting, who also happen to be neighbors, and it could be the last World Cup game for Cristiano Ronaldo.Spain appears to be rounding into form. It’s likely no coincidence that it has happened as Lamine Yamal has gained fitness. The 3-0 win against Austria last round was as comfortable as can be.La Roja have impressively not allowed a goal yet. The attack may not look as flashy as France’s and Yamal hasn’t starred like Lionel Messi for Argentina, but you can’t lose if you don’t give up a goal (at least not until penalties). Spain’s ability to control games makes it so hard for other teams to create chances.On paper, Portugal is the toughest team Spain has faced yet, but the performances haven’t lived up to the talented roster. A pair of draws against DR Congo and Colombia, in which Portugal had fewer shots than their opponents, were warning signs. The 2-1 win against Croatia last round was better in the attack, but was ultimately decided by tight offside calls and multiple VAR reviews.Spain has appeared to regroup and improve since a shocking 0-0 draw against Cape Verde in its opening match. Portugal hasn’t quite hit that same gear yet. That’s why Spain is the clear favorite with -220 or -230 odds, implying a better than two-thirds chance that Spain advances.As always, eyes will be on Ronaldo. The 41-year-old converted a penalty kick and had a goal called back for a close offside, but finished the match on the bench while Gonçalo Ramos, who didn’t start the match, scored Portugal’s game-winner in the 94th minute against Croatia. At this stage in his career, Ronaldo isn’t worthy of the attention he gets, but it’s hard to watch Portugal without focusing on what he is doing. Can he deliver a big moment against a team that will likely limit his chances?These Iberian neighbors have met at World Cups twice. In 2010, Spain won 1-0 in the round of 16 en route to its only world title. In 2018, they met in group play and played to a 3-3 draw in which Ronaldo scored a hat trick.United States-BelgiumTime: 8 p.m. ETTV: Fox (English), Telemundo (Spanish)Venue: Lumen Field, SeattleWhen the United States learned it would be a co-host for this World Cup, this is the kind of match the team would be looking forward to. This round has been a barrier for the U.S. men, who are 1-4 in the final 16 since 1994. One of those four losses came against Belgium in 2014.