Antanas Sireika (born May 11, 1956 in Bazilionai) is a retired Lithuanian professional basketball coach.
The Lithuanian national basketball team traditionally replaces the head coach with his assistant, this happened when Vladas Garastas was replaced by his assistant coach Jonas Kazlauskas. The story was repeated in 2001, when the successor of Kazlauskas was his assistant coach Antanas Sireika. He was born in à  iauliai, and a big part of his basketball career was spent there. Sireika played for à  iauliai, later he became the playing head coach of the team, in 1994 he ended his career as a player, and started coaching full-time. Big results came fast, the underdog à  iauliai, became 3rd-place winners in the LKL. In 1997, Kazlauskas became head coach of the Lithuanian national basketball team, and invited Sireika to join the squad as his assistant. In 2001, Kazlauskas retired from the national team, and gave his place to Sireika. With Sireika, the Lithuanian national basketball team won their first EuroBasket gold medals after Lithuania's independence in 1991 (the first titles came in 1937 and 1939).
The same year, Sireika made an important decision: he left his home in à  iauliai, and moved to Kaunas, to coach à ½algiris Kaunas. He won three LKL titles in a row in 2003, 2004 and 2005. At the 2004 Summer Olympics, Sireika coached the Lithuanian team to a 4th place with a memorable win against the United States.
Since 2003, à ½algiris Kaunas started to fade away from all the EuroLeague glory they had a few years ago. à ½algiris' EuroLeague results got worse every year. In the 2005âÂÂ06 season Sireika was dealing with huge amount of criticism aimed at him, because of poor results in EuroLeague and Lietuvos rytas Vilnius was at the top of the Lithuanian league standings. On March 28, 2006 in a LKL regular season rivalry game, Sireika's coached à ½algiris played against Lietuvos rytas and lost the match by 30 points. After the game Sireika left the team.
In EuroBasket 2005, Lithuania was named as one of the contenders to win gold and defend their 2003 title, Lithuanian team finished first in the group and entered quarter finals, where they lost 47âÂÂ63 to France led by Tony Parker. Lithuanian team took 5th place and even more criticism was aimed at Sireika. He had his last chance at an FIBA World Championship in 2006. Lithuania finished 3rd in the group entering 1/8 finals. In the quarterfinals they were defeated by Spain, and in fifth through eighth place games they lost to Turkey, Lithuania took 7th place, and Sireika resigned.
In 2006 summer, UNICS Kazan introduced Sireika as their new head coach, the Lithuanian trio: Lavrinoviàbrothers and Saulius à  tombergas led Unics into ULEB Cup semifinals, but the team lost to Real Madrid and did not enter the final. In the Russian Basketball Super League, UNICS surprised the league by finishing 2nd after the EuroLeague champions CSKA Moscow, and overcoming teams like Dynamo Moscow, Khimki and Triumph Lyubertsy. The 2007âÂÂ08 season did not start out well, as Russia's basketball experts had expected, UNICS was 8th in the Russian Super League, Sireika was dismissed from the head coaching position and moved to assistant.
In 2008 season Lietuvos rytas Vilnius haven't won anything, all domestic titles were lost to à ½algiris Kaunas. A few weeks after their loss in LKL finals, Lietuvos rytas Vilnius started to build a new team dismissing many former players, Aleksandar Trifunoviàwas dismissed as head coach, and Sireika was signed as the head coach. But just after 2 months, he resigned and returned to à  iauliai to become their head coach.
|- | style="text-align:left;"|Link Tochigi Brex | style="text-align:left;"|2012-13 | 42||13||29|||| style="text-align:center;"|6th in JBL|||-||-||-|| | style="text-align:center;"|- |- | style="text-align:left;"|Link Tochigi Brex | style="text-align:left;"|2013-14 | 54||31||23|||| style="text-align:center;"|3rd in NBL Eastern|||3||1||2|| | style="text-align:center;"|Lost in 1st round |-
|- | align="left"|à ½algiris | align="left"|2002âÂÂ03 | 9 || 4 || 5 || || align="center"|Eliminated in group stage |- | align="left"|à ½algiris | align="left"|2003âÂÂ04 | 20 || 9 || 11 || || align="center"|Eliminated in TOP-16 |- | align="left"|à ½algiris | align="left"|2004âÂÂ05 | 20 || 8 || 12 || || align="center"|Eliminated in TOP-16 |- | align="left"|à ½algiris | align="left"|2005âÂÂ06 | 19 || 9 || 10 || || align="center"|Resigned |-class="sortbottom" | align="center" colspan=2|Career||68||30||38||||