Júnior Alonso

Lille

Alonso joined French club Lille in a permanent transfer in January 2017. He made his debut for the club on 18 February 2017, coming on as a second-half substitute in a win over SM Caen. He would go on to make 56 appearances for Lille in all competitions before leaving on loan in August 2018.

Celta (loan)

On 14 August 2018, Alonso was loaned to La Liga's Celta Vigo for one year with an option to make the deal permanent.

Boca Juniors (loan)

On 2 January 2019, he was loaned to Boca Juniors. On 2 May 2019, Alonso was an unused substitute as Boca defeated Rosario Central in the 2018 Supercopa Argentina on penalty-kicks after the match ended 0–0.

Atlético Mineiro

On 2 July 2020, Alonso joined Brazilian club Atlético Mineiro on a four-year deal for a €3 million fee. He quickly became a starter on the team, and in 2021 he was champion of 2021 Campeonato Brasileiro Série A and 2021 Copa do Brasil, playing in 51 matches and scoring 1 goal, being captain and a pillar of defense.

Krasnodar

On 7 January 2022, Russian club Krasnodar announced that the terms of transfer has been agreed with Atlético Mineiro, and the terms of the 3.5-year contract has been agreed with Alonso. The contract was signed on 12 January 2022. On 3 March 2022, following the Russian invasion of Ukraine, Krasnodar announced that his contract was suspended and he would not train with the team, but the contract was not terminated and remained valid.

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Alonso is a full international for Paraguay, having made his senior debut for his country in 2013. In a 2018 FIFA World Cup qualifying match on 23 March 2017, Alonso scored the winning goal, and his first for the national team, in a 2–1 defeat of Ecuador. On 29 May 2019, Alonso was selected to the final 23-man roster for the 2019 Copa América in Brazil. He would go on to start in all four of Paraguay's matches, playing every single minute, as they lost in the quarter-finals in a penalty shoot-out to hosts and eventual champions Brazil. On 1 June 2026, he was named by head coach Gustavo Alfaro in Paraguay's 26-man squad for the 2026 FIFA World Cup.

Club

As of match played 27 May 2026.

International

As of 4 July 2026

Scores and results list Paraguay's goal tally first.

Club

Cerro Porteño

Paraguayan Primera División: 2013 Clausura, 2015 Apertura Boca Juniors

Argentine Primera División: 2019–20 Supercopa Argentina: 2018 Atlético Mineiro

Campeonato Brasileiro Série A: 2021 Copa do Brasil: 2021 Campeonato Mineiro: 2020, 2021, 2022, 2025

Individual

Bola de Prata: 2020, 2021 Campeonato Brasileiro Série A Team of the Year: 2021 Best Centre-back in Brazil: 2021 South American Team of the Year: 2021 Campeonato Mineiro Team of the Year: 2025