Whoever caught less than a Rak'ah of the Friday Prayer has missed it
Question :
On Friday, I went late to the mosque and caught only the Tahiyyat from its beginning and after the Imam made the Taslim, I stood up and completed what I had missed of the prayer? Was this prayer of mine complete and correct?
Answer:
Whoever caught less than a Rak'ah of the Friday prayer has missed the Friday prayer and he must perform a Zuhr prayer of four Rak'ahs. If he joins them in what remains of the prayer, that is, after the bowing in the second Rak'ah, he should join them with the intention that it is the Zuhr prayer, if the time for it - which is when the sun begins to set from its zenith - has already begun. If he does join the prayer with the intention of praying the Friday prayer, and he only made up two Rak'ahs, then there is no prayer for him, and the ruling is that he should repeat it as Zuhr prayer. And Allah knows best.
Source:
Ibn Jibreen
Fatawa Islamiyah, Vol. 2 Page 460