- Bats Left, Throws Left
Rivera was a native of the Dominican Republic but was in Italy by high school. He debuted in Italy's top league in 2011, throwing three shutout innings for Parma. He was 2-2 with a 6.00 ERA in 2012. In 2013, he was 3-3 with a 3.63 ERA for Parma but walked 39 in 67 innings. He picked off six runners, double any other hurler.  He went 0-2 with two saves and a 3.44 ERA in 2014, walking 20 in 34 IP. He was 10th with a .185 opponent average.  He won a Gold Glove and the Giulio Glorioso Award. 
Despite his wildness, the lefty made the Italian squad for the 2014 European Championship. He turned in a strong start against Sweden, allowing 2 hits, 3 walks and one run in 6 1/3 innings while fanning two; Nick Morreale relieved him and Rivera got the win. He also took one of Italy's two losses, both against the champion Dutch national team. In the last game of the second round, he lasted 4 1/3 innings and gave up a 3-run homer to Hainley Statia and a solo dinger to Yurendell de Caster.  In 2015, he fell to 0-6, 4.62 while switching teams to Rimini. He had the 2nd-highest ERA among qualifiers; only Alessandro Petralia was higher. Only Ronald Uviedo took more losses. 
Again, he was chosen for the Italian national team, this time despite having been one of the league's lesser hurlers. He got into one game, relieving Gianny Fracchiolla in the 6th with a 11-1 deficit against the Netherlands. He retired Gianfranco Wawoe but then gave up a double to Randolph Oduber, walked de Caster and Dwayne Kemp, gave up a sacrifice fly to Wladimir Balentien, a two-run double to Curt Smith and a RBI single to Kalian Sams before Statia grounded out. Ludovico Coveri took over in the 7th. Rivera finished with Italy's highest ERA as his 36.00 was more than double Filippo Crepaldi's 16.88. 
He was 1-2 with a 5.11 ERA in the 2016 IBL and had a 3.38 ERA in the 2016 European Champions Cup.  In 2017, he improved to 6-3 with a 3.76 ERA and a save for Rimini. He tied for 4th in the league in wins.  He returned to Parma for 2018 and was 0-1 with a 5.00 ERA. He allowed 3 unearned runs in 1 1/3 innings in the semifinals but had a 2.45 ERA in the 2018 Italian Series as Parma fell to Bologna. He was 3rd in the Series with nine strikeouts and tied Raul Rivero for 3rd in ERA. 
Rivera pitched 2 2/3 shutout innings in the 2019 European Champions Cup with three walks and five whiffs.  He went 2-1 with a save and a 4.50 ERA in the 2019 Serie A1 and pitched 5 2/3 shutout innings in the semifinals (1 H, 3 BB). He was very good in the 2019 European Championship, throwing 4 1/3 innings without a run and only two hits; he walked none and fanned five. In the Gold Medal Game, he relieved Matteo Bocchi with a 5-1 deficit in the 7th against the Netherlands. He gave up a Calten Daal single but picked him off then fanned former major leaguer Roger Bernadina and got Smith on a fly. Pugliese relieved him in the 8th.  Italy won a spot in the 2019 Europe/Africa Olympic Qualifier; in that event, he appeared twice. Against South Africa, he relieved Andrea Pizziconi in the 7th with a 4-4 tie, one on and one out. He retired Rowan Ebersohn and struck out Brett Willemburg. In the 8th, he allowed a Brandon Bouillon single but whiffed both Hein Robb and Dayle Feldtman and Benjamin Smith grounded out. Bocchi relieved in the 9th. His other game came against a familiar opponent, the Netherlands. He relieved Angelo Palumbo with one out in the 5th and a 4-1 deficit. He retired Bernadina but Hendrik Clementina and Ademar Rifaela both singled and Pat Venditte succeeded him.