By Jake Donovan

Day Five of Olympic boxing competition saw the action move to the Round of 16. 

Unfortunately for Team USA, what wasn’t seen was a return to its winning ways.

Joseph Diaz Jr. was valiant in defeat, as the 19-year old fell short to top-seed Lazaro Alvarez of Cuba by a score of 21-15. The scoring was a bit strange, but ultimately the right call as Alvarez deserved the nod regardless of the final margin.

The greatest dispute came in what appeared to be a sensation second round for Diaz Jr., who in the public eye did no worse than fight on even terms with Alvarez. The judges did not agree, as Alvarez was rewarded a three-point margin to turn a slight one-point lead after one to a comfortable cushion heading into the final round.

The U.S. corner expressed subtle disbelief in the Cuban being awarded 14 points after two rounds, but instructed their charge to just buckle down and fight his heart out. Diaz Jr. did just that, but was unable to close the gap. 

Team USA has now lost three straight after winning its first four contests. Diaz Jr. was the very first winner of 2012 Olympic competition, but now joins teammates Marcus Browne and Jamel Herring on the sidelines. 

Meanwhile, Alvarez advances to the quarterfinals, which played out as expected on paper. Not quite as predictable a result is his opponent. Brazil’s Robenilson Vieira pulled off a considerable upset with a narrow 13-11 points win over Sergey Vodopiyanov of Russia.

It was a familiar tale for Vodopiyanov, whose lack of activity and effective aggression cost him in the Round of 16 in the 2008 Olympics. The Russian once again fell on the short end, as Vieira built up a small lead early and fought on even terms for the rest of the contest. 

John Joe Nevin improves on his run in the 2008 Beijing Games, as the Irish bantamweight advances to the quarterfinals after scoring a 15-10 win over Kazakhstan’s Kanat Abutalipov. 

The win was a minor upset for Team Ireland, which remains perfect in 2012 competition (3-0). Nevin benefited from generous judging in the opening round, building on a 5-2 lead and then playing keep away in the final round to move within one fight of the medal round. 

Nevin will go on to face Oscar Valdez of Mexico, who managed a 13-7 win over Anjar Yunosov of Tajikistan. Valdez took advantage of the defensive style of his opponent, winning the fight purely on ring activity. Yunosov was a bit too slick for his own good, wasting unnecessary energy early on before running out of gas when it mattered the most.

Four more bantamweight Round of 16 bouts will take place later in the evening (London time). The first bout of the latter portion will feature the 2012 Olympic debut of Great Britain's own Luke Campbell, who was granted a 1st round bye. Campbell faces Vitorrio Parrinello of Italy.

Round of 16 Matchups (Wednesday, August 1):
Lazaro Alvarez (Cuba) def. Joseph Diaz Jr. (USA)  21-15
Robenilson Vieira (Brazil) def. Sergey Vodopiyanov (Russia), 13-11
John Joe Nevin (Ireland) def. Kanat Abutalipov (Kazakhstan), 15-11
Oscar Valdez (Mexico) def. Anjar Yunosov (Tajikistan), 13-7
Vitorrio Parrinello (Italy) vs. Luke Campbell (Great Britain/Received 1st round bye)
Ibraham Balla (Australia) vs. Detelin Dalakliev (Bulgaria)
Mohamed Ouadahi (Algeria) vs. William Encarnacion (Dominican Republic)
Satoshi Shimizu (Japan) vs. Magomed Abdulhamidov (Azerbaijan/Received 1st round bye)

Bantamweight Quarterfinals (Sunday, August 5)
Lazaro Alvarez (Cuba) vs. Robenilson Vieira (Brazil)
John Joe Nevin (Ireland) vs. Oscar Valdez (Mexico)

Jake Donovan is the Managing Editor of Boxingscene.com. Follow Jake on Twitter: @JakeNDaBox