Matheus KJ Santos Jungle Diniz is a Brazilian professional Dota 2 player who plays in the Full-support position.

KJ 's career started in 2016, his first notable results came in 2018, reaching the ESL Brazil Premier League finals with NoPing e-sports. In 2019, the team participated in the open qualifications for The International 2019 in South America, but did not make it to the tournament. That same year, they placed second at the World Electronic Sports Games 2019 Brazil Finals. In 2020, KJ and his team reached 7th-8th place at StarLadder ImbaTV Dota 2 Minor Season 3, won CBDota 2, Betsafe Invitational and Movistar Liga Pro Gaming Season 4, and were finalists at ESL One Los Angeles 2020 Online. In June, NoPing e-sports took a break and players played under the Team Brasil tag, where Mateus finished in the top 4 at OMEGA League: Americas Ancient Division and won Movistar Liga Pro Gaming Season 6.

In December 2020, Team Brasil signed with SG e-sports, immediately winning silver at the Movistar Liga Pro Gaming Final Series. In 2021, the team finished third at the OGA DPC South America Regional League Season 1: Upper Division, and sixth the following season. They were also second at INVie and Mobius.Bet Maestros, and made their way to The International 2021, finishing 17th-18th. After the tournament, the lineup broke up and KJ returned to NoPing e-sports, winning the Fallen Cup. In 2022, playing for Wolf Team, he finished second at DPC SA 2021/22 Tour 2: Division II and third at BTS Pro Series Season 12: Americas.

Since January 2023, KJ has been playing for Keyd Stars and with them reached the finals of Games of Future 2023, won the Fallen Cup Season 2 and finished in the top 4 at DPC SA 2023 Tour 1: Division I, but finished seventh at DPC SA 2023 Tour 2: Division I , dropping to the second division. In the fall of 2023, Matheus participated in The International 2023, where he finished 13-16th.

In January 2024, KJ joined the new Heroic roster. Together with him he participated in qualifications for BetBoom Dacha Dubai 2024, DreamLeague Season 22 and ESL One Birmingham 2024. The squad managed to qualify for DreamLeague and LAN in Birmingham, but at the closed qualification for the tournament in Dubai the team was one step away from victory, losing to Nouns in the grand finals of the tournament. Also, Heroic competed at Elite League 2024, PGL Wallachia: Season #1 and DreamLeague Season 23, and easily qualified for Riyadh Masters 2024 and The International 2024. At the Riyadh Masters, the team placed thirteenth. A little later, they finished tenth at Elite League Season 2, where they had previously received a direct invitation. In September, the guys went to TI13, but after the group stage fell to the lower bracket, where they were defeated by Aurora Gaming and left the championship.

In early October, the team went to PGL Wallachia Season 2, where they showed a great result, taking first place in the group. In the playoffs, the team advanced to the upper bracket final, where they were defeated by Team Falcons. Despite this, Heroic managed to take revenge against the Arab team in the grand final. It was the first time that the South American team became champions of such a major tournament and earned the first trophy for the region.

The next tournament for the team was DreamLeague Season 24, but Heroic was not so successful there and could not even get out of the group stage. At BLAST SLAM I Heroic also failed, placing 7-8th.

In February 2025, KJ with Heroic placed 8th at FISSURE PLAYGROUND and DreamLeague Season 25. In March, the team competed at PGL Wallachia Season 3, but failed to advance past the group stage. At the beginning of April, the team participated in ESL One Raleigh 2025, but they were also unable to reach the playoffs in this tournament, as well as at PGL Wallachia Season 4.

In June 2025, Heroic qualified for The International 2025 and also secured a slot at Riyadh Masters 2025, through the South American qualifier. However, at PGL Wallachia Season 5, the team once again failed to advance to the playoffs. On FISSURE Universe: Episode 5, the team finished in the top 4.

In July 2025, Heroic ended their participation in Riyadh Masters 2025, finishing in 14th place and earning $50,000 in prize money.

In September, Heroic participated in The International 2025, reaching the playoffs but losing in the lower bracket and finishing in 5–6th place.

At the end of October, Heroic participated in FISSURE PLAYGROUND 2, where they finished in 6th–8th place after losing in the first round of the Playoff stage. The team finished PGL Wallachia Season 6 with the same result.