Heck I'm also sure Juventus will not stay so long on the table but for now, Max Allegri has done well to push the lads to this particular position. They have a wide range of attacking players. Dusan Vlahovic gradually chasing Lautaro Martinez for the hunt for the highest goals scored.
I agree with you, Juventus can only be there for a week then after Inter Milan play their 21st match they will take over the top of the standings. Indeed, it will not be an easy match for Inter Milan but we know they will play as hard as possible I guess at least Inter Milan will get one point. Apart from that, Fiorentina is also not confident because they played badly in the last 2 matches, apart from that Inter Milan will soon face a decisive match against Juventus we can't predict who will win but Inter Milan has the advantage of playing as host.
After winning 3-0 over Lecce, Juventus will temporarily feel happy because they can be at the top of the standings this week. But whether it will be long or short is not certain.
But my prediction is that Inter will definitely win when they face Fiorentina. Even though Inter has another match scheduled for this week (the Italian Super Cup final against Napoli), it seems that Inter will not waste the opportunity to overtake Juventus, who have just risen to the top of the standings (Serie A).
So even though this week Inter Milan has a schedule that is definitely quite tiring. However, when facing Fiorentina, I am sure the Inter Milan players will be fit. The reason is that if Inter Milan loses when competing against Fiorentina, it is very likely that Juventus will sit at the top of the standings for more than 1-2 weeks and Inter Milan will definitely have a little difficulty shifting them. So the match against Fiorentina was actually quite a decisive match for Inter Milan. Because if they lose, Inter Milan will really have to fight harder to overtake Juventus.