"Messi will play, because he always wants to play and I love that," he told a news conference on Monday.
"We had been thinking of giving him a rest but to have a player of the class of Leo, the best in the world by a long way without doubt, it would have been a sin not to give him to the team, to the people, not give ourselves (the pleasure).
"When I told him, he was super happy," added Maradona at the Loftus Versfeld stadium near Argentina's tournament base on the eve of the match at Polokwane.
Juan Sebastian Veron, who Maradona confirmed was returning from the calf muscle injury he suffered against Nigeria, would normally captain the side in Javier Mascherano's absence.
However, holding midfielder Mascherano is one of eight changes Maradona has decided or been forced to make from the team that started in the 4-1 win over South Korea on Thursday.
Asked if he had ever thought of making Messi his captain, Maradona said enigmatically: "You'll know tomorrow."
PLAYERS RESTED
Wing back Jonas Gutierrez is suspended, Mascherano and fullback Gabriel Heinze are on one booking each, while strikers Carlos Tevez and Gonzalo Higuain are among the players rested with Sergio Aguero and Diego Milito taking their places.
Argentina lead the group after beating Nigeria 1-0 then South Korea. A draw with Greece will be enough to win it.
If Messi can score his first goal at this World Cup against the nation that conceded the last of Maradona's 34 international strikes so much the better, added the coach, who began the news conference by showing off a flashy, diamond-studded pair of sunglasses given to him on Father's Day on Sunday.
"I would love it for Leo to take the baton of the goal in that match," Maradona said referring to Argentina's 4-0 win over Greece at the 1994 finals, the teams' only previous meeting, in which Maradona scored and Gabriel Batistuta got a hat-trick.
"Above all because of the move which started in midfield... I hope Leo can score a similar goal, or better, or one that trickles agonisingly over the line but is a goal."
