In the 2002–03 season, the Serie A, the major football Italian professional league, was composed by 18 teams, for the 15th consecutive time from season 1988–89.
The 2002–03 season was the 103rd season in Società Sportiva Lazio's history and their 15th consecutive season in the top-flight of Italian football. Lazio finished fourth in Serie A and reached the semi finals of both the Coppa Italia and UEFA Cup.
The 2003–04 season was the 104th season in Società Sportiva Lazio's history and their 16th consecutive season in the top-flight of Italian football. Lazio finished sixth in Serie A, however, won the Coppa Italia this season.
The 2002–03 season saw great success for Associazione Calcio Milan. Milan won both the Coppa Italia and the Champions League, defeating Juventus on penalties after a 0–0 draw.
The 2002–03 season was Football Club Internazionale Milano's 94th in existence and 87th consecutive season in the top flight of Italian football.
Parma Associazione Calcio regained its respect following a lacklustre Serie A and Champions League performance the year before. Under new coach Cesare Prandelli, Parma played an offensive 4–3–3 formation, in which new offensive signings Adrian Mutu and Adriano starred. Both made up for the departure of Marco Di Vaio to Juventus. Mutu scored 18 goals from the left wing, and Parma accepted a multimillion-pound offer from Chelsea in the summer, which meant the Romanian international only spent a year at the club. Also impressing were goalkeeper Sébastien Frey and young centre-halves Matteo Ferrari and Daniele Bonera, who proved to be acceptable replacements for departed captain Fabio Cannavaro, who had joined Inter in late August 2002.
Associazione Sportiva Roma crashed down to earth following its previous two remarkable seasons, where it had won Serie A in 2000–01 and finished a close second in 2001–02. Despite the acquisition of Pep Guardiola as central midfielder, he did not apparently fit into Fabio Capello's first-team plans. The squad was essentially the same as the year before, and Guardiola's absence from the starting XI spoke volumes about the reputation of the Roma players at the time. However, things began to go against Roma following its tense competition in Serie A with Juventus. Suspecting things were amiss, both chairman Franco Sensi and manager Capello publicly condemned the judgements, and given the Calciopoli scandal in 2006, chances are they had a point.
Udinese Calcio bounced back from the hugely disappointing 2001–02 Serie A season, in which it only just managed to avoid relegation. Under new coach Luciano Spalletti, Udinese gathered strength, and was a constant feature on the top half of the league table. Even though the squad lacked the goalscoring punch, the defence led by Néstor Sensini and surprising goalkeeper Morgan De Sanctis held it together to such a degree it finished sixth in the league. Also Czech signing Marek Jankulovski impressed, the Napoli signing switching form left-wing to left back, causing interest from several bigger clubs. In the offence, Udinese's most influential player was David Pizarro, who scored seven times from the midfield and grabbed the attention from Lazio, who tried to sign him and teammate Martin Jørgensen immediately after the season had finished. Undisclosed Lazio players refused moving to Udine as compensation for the transfers, and both stayed on, much to the relief of Spalletti.
Associazione Sportiva Roma was left trailing in the wake of city rivals Lazio's resurgence to fight for domestic and international glory. In coach Zdeněk Zeman's second season at the reins, Roma finished fifth in the table, and just missed out on qualification for the final Champions League spot. Roma reached the quarter-finals of the UEFA Cup, but lost to Atlético Madrid.
A.C. Perugia finished tenth in Serie A, and reached the semis of the Coppa Italia in a successful season by the clubs' standards.
A.C. ChievoVerona played its second consecutive season in Serie A, and nearly equaled 5th place from the 2001-02 Serie A season. The club's second season in the premier division was played without Christian Manfredini and Bernardo Corradi, both ending up with Lazio. Due to passport troubles, it also lost key winger Eriberto, who turned out to be four years older and called Luciano, but had faked his identity since he was 21, in order to participate in a Brazilian youth team.
ACF Fiorentina returned to Serie A, following a two-year absence after the bankruptcy of the previous incarnation of the club. Fiorentina returned only due to the expansion in terms of the number of top-league teams, and therefore had to significantly strengthen the squad in pre-season. Dario Dainelli, Giorgio Chiellini, Hidetoshi Nakata, Fabrizio Miccoli, Martin Jørgensen, goalkeeper Cristiano Lupatelli, Enzo Maresca, Tomáš Ujfaluši and Javier Portillo were among the highly rated players to sign up for Fiorentina, either permanently or on loan. With this squad, Fiorentina was expected to challenge for a place on the top half of the table, but slipped into the relegation battle that affected more than half of the Serie A clubs during the dramatic season. In the end, a strong finish to the season under incoming coach Dino Zoff saved La Viola from relegation, with an emotional 3–0 victory against Brescia confirming their survival.
Associazione Sportiva Roma was reinvigorated under new coach Zdeněk Zeman, who recently had been coaching arch rivals Lazio. Zeman brought his attacking 4–3–3 with him, resulting in Roma scoring 67 goals, but also conceding 42, an extreme rarity in defensive-minded Italian football. Roma finished fourth, three places above Lazio in the table. That was the first time it had happened in five years, which delighted the Roma board, and Zeman stayed on for a further season. The season also saw the international breakthrough of former youth-team product Francesco Totti, who at 21 was ready for increased responsibility and captaincy, responding with 13 league goals from a position on the left-wing of the attack. Also noticeable was new signing Cafu's offensive skills as a right-wing back, granting him a reputation among the world's top wing backs.
Reggina Calcio just renewed its Serie A contract, thanks to a late surge in the league competition and a successful spareggio against Atalanta. Reggina drew 0-0 at home, and then turned around a deficit to win 2-1 away from home, with Francesco Cozza and Emiliano Bonazzoli being the match-winners. The player who got the most headlines during the season was Japanese playmaker Shunsuke Nakamura, who scored seven goals and created several others. He also helped Reggina to get onto the Asian market, so the signing was largely hailed as a genial manoeuvre by president Pasquale Foti.
Reggina Calcio did renew its Serie A contract on the second consecutive occasion, ensuring the longest stay of the Calabrian club in the top division of Italian football. With returning coach Franco Colomba not being successful in his third stay at the club, Giancarlo Camolese guided the side to 13th place in the league. With only 29 goals scored, Reggina relied heavily on its defence for the survival, and Martin Jiránek plus defensive midfielder Davide Baiocco strengthened their reputations. After the season, Baiocco returned to Juventus, who in turn loaned him out to Reggina's arch-rivals Messina, newcomers for the 2004–05 season, setting up the first Messina strait derby in the highest division ever.
Atalanta B.C. lost its momentum it had built in its first two Serie A seasons in its stint, eventually being relegated following a playoff against Reggina. The championship was such competitive than Atalanta was only four points away from repeating its 9th place from the 2001-02 season, but instead had to face Serie B competition, losing key players such as Cristiano Doni, Luciano Zauri and Ousmane Dabo to bigger clubs.
Piacenza Calcio had the highest-scoring season in the club's history, but in spite of this, a defeat to Verona in the final round would have rendered relegation. Two goals from Dario Hübner helped sealing a 3–0 victory, which propelled Hübner to become top scorer of the entire Serie A, tying for 24 goals with David Trezeguet. The ex-Brescia hitman Hübner came following the promotion, and aged 34, he reached the very top of his level.
During the 2002–03 Italian football season, Brescia competed in the Serie A.
During the 2003–04 Italian football season, U.S. Lecce competed in the Serie A.
