...none aliances were formed...
I don't think that the ottoman military was more advanced...
Wrong.
Ottoman military formed new units and used advanced arms and tactics.
Let's see 3. ruler of Ottoman Empire:
Murad I (nick-named Hüdavendigâr, "the God-like One") (Turkish:I.Murat Hügavendigâr) (1319 or 1326 – 1389) (Arabic: مراد الأول

was the ruler of the Ottoman Empire from 1359 to 1389. He was the son of Orhan I and the Byzantine princess Helen (Nilüfer) who was of ethnic Greek descent[1][2][3], and became the ruler following his father's death in 1359.
He established the Empire by building up a society and government in the newly conquered city of Adrianople (Edirne in Turkish) and by expanding the realm in Europe, bringing most of the Balkans under Ottoman rule and forcing the Byzantine emperor to pay him tribute. It was Murad who established the former Osmanli tribe into an empire. He established the title of sultan in 1383 and
the corps of the janissaries and the devşirme recruiting system. He also organised the government of the Divan, the system of timars and timar-holders (timariots) and the military judge, the kazasker. He also established the two provinces of Anadolu (Anatolia) and Rumeli (Europe).
Murad fought against the powerful emirate of Karamanid in Anatolia and against the Serbs, Bulgarians and Hungarians in Europe. His moves in the Balkans brought together
a Christian coalition under the king of Hungary, but they were defeated at the Battle of Maritsa on September 26, 1371 by Murad's capable second lieutenant Lala Şâhin Paşa, the first governor (beylerbey) of Rumeli. In 1366 the Serbian king was forced to pay tribute to the Sultan and in 1385 Sofia fell to the Ottomans. In 1389 Murad's army indecisively defeated a Balkan Christian army at the first Battle of Kosovo. After the battle, Murad I was assassinated by Milos Obilic, a Serbian noble who earlier swore that it would be his sword that would kill Murad. (see the conquests of Murad I).
The Battle of Maritsa
The Battle of Maritsa or Battle of Chernomen (also known as the Second Battle of Maritsa) took place at the Maritsa River near the village of Chernomen (today Ormenio in Greece) on September 26, 1371 between the forces of the Ottoman sultan Murad I's lieutenant Lala Şâhin Paşa and the Serbs (including their Bulgarian allies) numbering some 70,000 men under the command of the Serbian king of Prilep Vukašin Mrnjavčević and his brother despot Uglješa.
Despot Uglješa wanted to make a surprise attack on the Ottomans in their capital city, Edirne, while Murad I was in Asia Minor.
The Ottoman army was much smaller, but due to superior tactics (night raid on the allied camp), Şâhin Paşa was able to defeat the Christian army and kill King Vukašin and despot Uglješa. Macedonia and parts of Greece fell under Ottoman power after this battle.
The battle was a part of the Ottoman campaign to conquer the Balkans and was preceded by the Ottoman capturing of Sozopol and succeeded by the capture of the cities of Drama, Kavála and Serrai in modern Greece.
Later on
Now that the Serbian coalition was weakened by such a blow, Murad was quick to advance further into Bulgaria and capture the cities of Dráma, Kavála and Seres (Serrái).
In 1383 Murad declared himself sultan of the Ottoman Empire. Shortly thereafter he began a new campaign in Europe. Sofia fell in 1385 and the city of Niš the year after. The Ottoman Conquest halted in 1387 when the Serbs won the Battle of Plocnik but two years later Murad marched anew into the west. The Ottomans won a great victory over the Serbs in the Battle of Kosovo but the sultan himself was killed on the end of battle . His son Bayezid stands after his murder.
ref: wiki