*Club domestic league appearances and goals, correct as of 07:42, 22 September 2024 (UTC) ‡ National team caps and goals, correct as of 17 October 2023 (UTC)
On 23 April 2016, Krstović made his competitive debut for Zeta, being assigned the number 13 jersey. He came on as a second-half substitute for Filip Kukuličić in their 1–1 league draw away against Iskra Danilovgrad, becoming the youngest player ever to appear in a 1. CFL game at the age of 16 years and 18 days old.[2] Until the end of the 2015–16 Montenegrin First League, Krstović would go on to play in three more fixtures (all as a substitute) as the club hovered around the middle of the table.
On 5 November 2016, Krstović made his first appearance of the 2016–17 season, entering the field during the second half of a 1–0 home league win over Bokelj. He scored his first senior goals in March of the following year, netting a brace in a 3–0 away victory over Jedinstvo Bijelo Polje,[3] making him the first player born in the 2000s to find the back of the net in the top flight of Montenegrin football.[4] In his first full season at Zeta, Krstović played in 19 games (all in the league) and bagged seven goals.[5]
On 29 June 2017, Krstović appeared as a starter for Zeta wearing the number 9 shirt in a 1–0 away loss to Željezničar Sarajevo in the first leg of the 2017–18 UEFA Europa League first qualifying round. He later scored an equalizer in the return tie a week later at home (the game ended in a 2–2 draw).[6] In October of the same year, Krstović netted his first senior hat-trick and led his team to a 4–2 home win over Kom.[7] He tallied 15 goals in 39 matches across all competitions throughout the season.
Red Star Belgrade
On 25 February 2019, Krstović signed with Serbian club Red Star Belgrade until the summer of 2023 with an option for another year.[8] He remained on loan at Zeta until the end of the season, becoming the Montenegrin First League top scorer with 17 goals.[9]
DAC 1904 Dunajská Streda
On 5 September 2021, DAC has announced the signing of Krstović on a four-year contract. DAC's sporting director Jan Van Daele claimed that DAC had scouted Krstović since his youth years in Montenegro. He was given the jersey number 45. Krstović claimed gladness and honour following the contract signing.[10] In 2022–23 Fortuna Liga season, Krstović became the league's top scorer, scoring 18 goals in 27 appearances, up from 4 goals in 11 matches in the previous season.[11]
On 17 August 2023, he was signed by Italian Serie A side Lecce and on 27 August he scored on his debut against Fiorentina, securing a 2–2 draw. Then he scored the opening goal at the Stadio Via del mare as giallorossi beat Salernitana 2–0 and a goal in a draw against Monza (1-1), thus becoming the first Lecce player to score in his first three games with the club.