US national team supporters are probably licking their chops at Thursday's quarterfinal matchup against Ecuador (June 16, 9:30 pm ET on FS1, UniMás and UDN). They can sense that the goal set by US manager Jurgen Klinsmann before the tournament – reaching the Copa America semifinals – may actually be within reach.


Be careful what you wish for.


Here are three reasons Ecuador could prove a tricky opponent for the Americans in their path to the Copa America semifinals:


(1) World-class forward: Striker Enner Valencia is fast and shifty and his quick accelerations will create a match-up problem for US center backs John Brooks and Geoff Cameron. The good news for the USA is that the equally slippery former MLSer Miller Bolaños is ruled out due to injury, a significant loss for Ecuador in the withdrawn forward position.


But perhaps the most influential players are Ecuador's wingers, who essentially serve as the team's playmakers: English Premier League-based duo of Antonio Valencia and Jefferson Montero. With US right back DeAndre Yedlin serving a red-card suspension and left back Fabian Johnson experiencing a quiet, sub-par Copa America, the US might run into big-time trouble here.


(2) Athleticism & physicality: If US fans thought their last match against Paraguay was a battle, Ecuador are even more physical and athletic from the goalkeeper position all the way to the forwards (see more below).


(3) This is the best Ecuador team in history: They are riding a wave of confidence that's been building over several years. They're ranked No. 13 in the world and they have more world-class players than they've ever produced. They've qualified for three of the last four FIFA World Cups and they're currently at the top of South America's World Cup qualifying standings after six matches.


HOW ECUADOR PLAY


There's nothing complicated about Ecuador. They trot out a 4-4-2 and they're looking to strip you of the ball, run at you with numbers and slice through your defense with quick combinations.


Teams that sit back can frustrate Ecuador because La Tri prefers to have their front four running at defenders and into space with a full head of steam. If the opposition can stifle their wing play and limit the Ecuadoreans to low-percentage crosses, the South American side can be neutralized.


ECUADOR'S STARTING XI (4-4-2)


GOALKEEPER: After Ecuador opened the Copa America tournament with the rarely-used Esteban Dreer, who had a standout performance against Brazil, they went back to the more experienced and athletic Alexander Dominguez.


DEFENDERS: Every member of the four-man backline is tall, athletic and physical and they're not too shabby with the ball at their feet either. The fullbacks -- Juan Carlos Paredes (right back) and captain Walter Ayovi (left back) – are experienced and established.


The center-back pairing will be comprised of 6-foot-2 newcomer and Copa Libertadores revelation Arturo Mina and 31-year-old Gabriel Achilier. Cover is provided by 6-foot-3 Frickson Erazo, who plies his trade in Brazil and stepped in for the suspended Achilier vs. Haiti.


MIDFIELDERS: Ecuador field a regular foursome in the middle. The stars and de facto playmakers are the wingers: Manchester United man Antonio Valencia wide right and Swansea City speedster Jefferson Montero wreaking havoc on the left.


The two central midfielders are defensive-minded: Russia-based Cristian Noboa and FC Dallas man Carlos Gruezo. Their mission is to break up opposing attacks, launch their own counters and provide overall balance and bite to the team.


FORWARDS: This is the fun part of the field for Ecuador. Goals in the English Premier League have not been plentiful for Enner Valencia, but when he joins his national team the dynamic changes. He's the focal point for La Tri and the team plays for him. Valencia is fast, unrelenting and he's clinical in front of goal, capable of scoring in any number of ways.


Valencia had formed a dynamic partnership with a former MLS player Miller Bolaños, who essentially served as a central playmaker. But a left hamstring strain suffered in the second group match will keep Bolaños out for the second straight Copa America match. He'll be replaced in the lineup by the powerful Jamie Ayovi (he got the nod vs. Haiti), who's also carrying a knock, or speedsters Fidel Martinez, Juan Cazares or Michael Arroyo.


BENCH: When he makes his subs, Ecuador head coach Gustavo Quinteros is typically thinking attack and he seeks to keep his forward line and wingers fresh and explosive. Here are his usual go-to men: forwards/wingers Ayovi, Martinez and Cazares. The next line of options include Arroyo (typically a left winger) and Angel Mena (right winger).


Should Ecuador need more creativity in the middle of the field, Fernando Gaibor will replace one of the center mids (Noboa or Gruezo).


USA vs. Ecuador History


The Americans have just three wins against Ecuador in 13 all-time meetings since 1984 (3-5-5 record). The latest victory came in a pre-Copa friendly in Frisco (1-0 on May 25), but before then the last win dated back to March 2007.


The only match between the two nations in an official competition came in the 1993 Copa America, a 2-0 Ecuador victory in a tournament they hosted. All 12 other matches have taken place on US soil.


Nov. 30, 1984: USA 0, Ecuador 0 (Friendly - Hempstead, N.Y.)
Dec. 2, 1984: USA 2, Ecuador 2 (Friendly - Miami, Fla.)
June 7, 1988: USA 0, Ecuador 1 (Friendly - Albuquerque, N.M.)
June 10, 1988: USA 0, Ecuador 2 (Friendly - Houston, Tex.)
June 12, 1988: USA 0, Ecuador 0 (Friendly - Fort Worth, Tex.)
June 19, 1993: Ecuador 2, USA 0 (Copa America - Quito, Ecuador)
Aug. 7, 1997:USA 0, Ecuador 1 (Friendly - Baltimore, Md.)
June 7, 2001: USA 0, Ecuador 0 (Friendly - Columbus, Ohio)
March 10, 2002: USA 1, Ecuador 0 (Friendly - Birmingham, Ala.)
March 25, 2007: USA 3, Ecuador 1 (Friendly - Tampa, Fla.)
Oct. 11, 2011: USA 0, Ecuador 1 (Friendly - Harrison, N.J.)
Oct. 10, 2014: USA 1, Ecuador 1 (Friendly - East Hartford, Conn.)
May 25, 2016: USA 1, Ecuador 0 (Friendly - Frisco, Tex.)