Allegri tests a 4-2-3-1 to fit De Bruyne, Vergara and Højlund together

Napoli used the international break for more than recovery. At Castel Volturno, head coach Allegri tested a system that had never come up before in planning for Frosinone: the 4-2-3-1.

The friendly against Avellino on 2 October already gave a partial answer. Allegri stuck with the 4-3-3, pushing Neres into a central midfield role, and dropped the week's talk of a back three built around Di Lorenzo at centre-back. The 4-2-3-1 is a third option now on the table, designed specifically so none of the three misses out in midfield or behind the striker.

The case for each of them is strong. De Bruyne scored twice in Belgium's 3-0 win over Turkey, though a yellow card will rule him out of the Nations League game with France. Vergara made his senior international debut in Saint-Denis, playing around half an hour and getting involved in the build-up to Bastoni's goal in the 1-1 draw with France. Højlund scored in Denmark's 2-2 with Portugal, a game Denmark went on to lose 4-2, and celebrated by copying Cristiano Ronaldo's trademark leap. Three different stories, one shared message: all three are back at Castel Volturno with something extra to prove.

Quality is there — balance is the question

The issue is less the system than how it is played: Napoli will need balance, the right attitude and each player finding his best form within it. With De Bruyne as the central No. 10 and Vergara and Højlund either side of him, Napoli would gain quality and unpredictability in attack. But the 4-2-3-1 offers less protection in front of the defence, a problem given what has gone wrong in Napoli's recent matches. Three times this season, against Como, Inter and Fiorentina, the team took the lead and then fell apart within a few minutes. A more attacking system could make that flaw worse, particularly if McTominay, whose availability will not be clear until Tuesday 6 October after heart surgery, is unable to play.

Napoli are ninth with 7 points after five matchdays, having drawn in Florence to stretch their unbeaten run to two games without resolving the bigger concerns over their league position. Allegri has five days to decide. Frosinone visit the Maradona on Saturday 10 October at 20:45 CET (19:45 UK, 14:45 ET), and the choice between the 4-3-3, the 3-4-2-1 and the new 4-2-3-1 will show whether this version of Napoli really can change shape, or whether it is still just an idea worked on in training.