I lob you

One of Faith’s opponents hit a lob from the baseline that was clearly going out. Before the ball landed out, the partner of the player who had hit the lob noticed a ball rolling onto the court and called a let.

Should they play a let?

Yes, since a ball rolled onto the court from another court, a let should be played.

No, since the lob had already been hit before the ball rolled onto the court.

No, since the lob was going out anyway.

I’m not sure.