That's an excellent question. I'm going to assume you mean the Lepanto opening moves that Austria and Italy use to take down Turkey, usually involving a convoy to Syria.
If you look at the first image on
https://imgur.com/a/87ywnSZ, you can see Turkey has no chance to truly stop the Lepanto. They build a fleet in Smyrna and can prevent a move to EastMed, but not to Aegean (since Austrian support is expected). Alternatively, Austria could move Greece to Aegean while Italy moves to EastMed, of which you can only prevent one. Turkey is in trouble.
Look at the second image though
https://imgur.com/a/87ywnSZ. Turkey has a fleet in Aegean and builds another in Smyrna. Nonetheless they have to guess correctly every turn whether Italy moves to Eastmed, or to Aegean with support. If Russia is 100% on your side though, R/T have some good moves available if you factor in Rum-Serb, Sev-Rum S BLA.
In conclusion, you cannot stop the Lepanto with tactics alone. If Russia is fully on your side, you can have the upper hand but that puts Turkey completely at R's mercy.
The best way to prevent the Lepanto is with diplomacy. Tactically, my strategy is to make sure Italy gets nothing from the attack while Austria takes Bulgaria. This will hopefully upset the balance enough that one of A/I stabs the other.
I've added a bonus image on
https://imgur.com/a/87ywnSZ (third one). By swapping Con and Sevas (which is madness), the Lepanto is stopped. However, Bulgaria can still fall. The seas are safe for now though.