Although he hasn't scored a perfect hat-trick in his professional career, there was a game back in the 2003/04 season where he did, playing for Barcelona C in the Tercera División. So without further ado, let's look at the perfect hat-trick.
It was January 4th, 2004. His first game of the new year would be against Gramenet B away. Both were in the relegation zone, so it was an important game to get out of trouble. Barcelona C had never been relegated from Tercera División since they got promoted in 1977, which was another factor.
Pedro gave Gramenet B the lead 19 minutes in, but Messi equalized with a header after a great cross from one of his team-mates. In the second half, Rúa gave Gramenet B the lead, but after Alberto got a red card, Messi came to save the day with a great strike with his left foot at the 89-minute mark, and on added time, he shot the ball with his right foot which went past the goalkeeper and a defender, making it 3-2 for Barcelona C. He received an ovation from the crowd according to Mundo Deportivo. This is the video detailing all 3 goals:
The following day, J. M. Roca, writer of Mundo Deportivo, gave Messi a 4/5, making him the MoTM, and he also called him a great player (a 'crack').
Barcelona C ended up in 9th place with 51 points, 9 away from relegation, while Gramenet B ended in last place with only 25 points, so his performance was significant. I hoped you liked this entry, and as always, I'll see you in the next blog.
After scoring an impressive 37 goals in 30 games with Barça's Cadete A, being the star player of Barça's best Cadete side ever, which didn't lose a single game and won the league, Copa Catalunya and the Spanish Championship, he was promoted to Juvenil B. It would be the beginning of a rollercoaster of a season for him, playing in 6 different teams overall.
He made his debut against Feyenoord in the U-17 Club World Cup final, assisting Songo'o's equalizer, and later winning the game 3-1. Shortly after, he won the José Luis Ruiz Casado Memorial 6-0 against Betis 6-0 with a brace and assist from him, and then the J. Gil Alonso Final against Espanyol 2-1 with a goal from him. After seeing those performances, he was quickly promoted to Juvenil A.
With Juvenil A, he made his debut against Hércules with a goal and won 3-0. He had an ankle injury in early October but quickly recovered from it. Afterward, he got his first poker of the season against Gimnàstic in Barça's 7-0 win. A bit over 2 weeks later, he scored a hat-trick against Granollers, and Rijkaard was made aware of his talent, and so, he was selected for a friendly against Porto.
November 16th, 2004, that was the day of his unofficial debut in Barcelona against Porto after being subbed on 74 minutes in. He had 2 good scoring chances but he unfortunately couldn't convert. Still, he made a good performance despite Barça losing 2-0.
Not long after, he made his debut in Barcelona C against Europa, winning 2-1. And before the end of the year, he won the Trofeo Ciudad de Nerja with Juvenil A, making 2 assists in Barça's 2-0 win in the semi-final against Málaga then 2 goals against Real Betis in the final, winning 3-2.
Entering 2004, after scoring a hat-trick against Gramenet to win Barcelona C the game 3-2, and some other good performances with the C team, he played once against with Barça's senior team, this time against Shakhtar Donetsk, entering in the second half.
Not long after, on March 6th, he made his debut with Barcelona B against Mataró, winning the game 1-0 though getting a yellow card. He made a few other performances with the B team before returning to Juvenil A and bagging a hat-trick against Vilobi in a 5-1 victory.
In the final games of the season with Barcelona, he returned to Juvenil B after getting injured over a week, and he ended up winning the league title with them on May 8th. His last games were with Juvenil A in the Copa del Rey Junior, scoring a poker against Sevilla in the R16, helping with a goal and an assist in Barça's 4-1 aggregate victory over Real Sociedad in the QF, then finally getting eliminated by Osasuna due to away goals, scoring a brace in the first leg.
After seeing those performances from him (40 goals and at least 6 assists in 46 games), and rejecting Spain's offer to play for them, he was called up for the U-20 Argentinian national team. He made his debut on June 29th against Paraguay, scoring an amazing solo goal starting halfway the pitch and giving 2 assists as well in Argentina's 8-0 victory. A few days later, he played against Uruguay in his last game of the season and made a brace as well as giving an assist in Argentina's 4-1 victory.
Overall, it was an amazing experience, starting at Juvenil B and ending up in 2 friendly games with the senior team and breaking havoc all the way up to Barcelona B, even getting called up for the U-20 national team, so it's safe to assume this was Messi's breakthrough season in terms of talent before officially making his debut in the senior team.