The round of 16 involves 16 players and 8 matches, followed by 4 quarterfinal, 2 semifinal and 1 final matches. Now that the simple math is behind us, let’s take a look at who remains in the mix of ingredients at Erin Hills, 2017 US Open site, in Wisconsin, lower 48, USA.

~One defending champion: Peter Uihlein, victory at Chambers Bay in 2010, member of the USA Walker Cup side in 2009 and 2011, would normally be in his own orbit, save for…

~Two young and incredible Patricks: Messrs. Cantlay (he of the PGA Tour fame) and Rodgers (he of the Porter Cup comeback) are having electrifying summers. Cantlay’s failure to close out Ethan Tracy two weeks ago in the Western Amateur final match bothered me a bit, as did Rodgers’ first-round match loss (albeit in 21 holes) to Andrew Yun.

~Two GBI (Great Britain & Ireland) Walker Cup stalwarts. Jack Senior and Tom Lewis want to take the US amateur trophy with them when they leave for Europe. Such a victory would create a wave of belief for a team that has lost three consecutive matches and is in need of a win to keep its participation relevant.

~Two Walker Cup hopefuls: Scott Langley has one match for the world. Defeat Peter Uihlein in the 16s and you just might make the Walker Cup side. I believe he needs at least one more win beyond that, to show that he can get up for a big match, then follow it with another big win. Jordan Spieth has shown that he can win major junior tournaments and add a wrinkle to adult amateur events. He has a fairly open road quarters through Ben Geyer of St. Mary’s College, but anything can happen if Spieth isn’t on his game.

~Two Walker Cup darkhorse candidates: John Hahn and Jordan Russell have made waves out of Kent State and Texas A&M, respectively, but neither has the signature victory nor the consistent top-15 track record at major amateur events. As they say, win the Amateur and you make the USA Walker Cup side.