Team 7 under Kakashi was ordered to go to the land of fire to handle a S-rank mission. As it was a very difficult mission, the members of the team 3 was ordered to joined them under Kakashi as well

Kakashi: "Everyone will be calm ! Team 3 will join us for the mission"

Sakura: "Ughh- why ? I hate that girl Shikuza" she said rolling her eyes

Naruto: "That will be cool Sensei. I will have my Kuna with me" he is happy either way

Sai: "Interesting" he said with his smile