Blues boss Antonio Conte first implemented the change for Chelsea’s trip to Hull last October after the west Londoners had suffered back-to-back league defeats to Liverpool and Arsenal.
The 3-4-3 set-up immediately worked as Chelsea beat Hull 2-0 away before storming to the Premier League trophy with a record-breaking 30 wins.
The champions have retained the 3-4-3 formation this season and Azpilicueta, who has had to move from left-back to the right side of a three-man defence in the new set-up, says he knew it would work.
“I’m enjoying it a lot,” the Spaniard told Chelsea’s official website. “For me, it was a new position, a new challenge.
1/30 Chelsea 2 West Ham 1
Diego Costa scores a late winner to earn Antonio Conte his first Premier League win.
2/30 Watford 1 Chelsea 2
Michy Batshuayi shines as the Blues secure another late win.
3/30 Chelsea 3 Burnley 0
Victor Moses caps off a comprehensive victory at Stamford Bridge.
4/30 Hull 0 Chelsea 2
Antonio Conte’s side recover from a poor run of results to beat Hull using their new 3-4-3 formation.
5/30 Chelsea 3 Leicester 0
Eden Hazard celebrates his goal either side of strikes from Diego Costa and Victor Moses.
6/30 Chelsea 4 Manchester United 0
The Blues humiliate Jose Mourinho on his return to Stamford Bridge with a stunning victory in west London.
7/30 Southampton 0 Chelsea 2
The Blues’ winning run goes on with victory at St Mary’s Stadium.
8/30 Chelsea 5 Everton 0
Antonio Conte’s switch to the 3-4-3 system continues to pay off – with his team thrashing the Toffees.
9/30 Middlesbrough 0 Chelsea 1
Antonio Conte celebrates with Diego Costa at full-time after the striker’s 41st-minute goal is enough to secure all three points at the Riverside Stadium.
10/30 Chelsea 2 Tottenham 1
Pedro and Victor Moses are on target as the Blues beat their London rivals despite going behind to Christian Eriksen’s opener.
11/30 Manchester City 1 Chelsea 3
The Blues complete another superb comeback which is capped off by Eden Hazard’s 90th-minute goal at the Etihad Stadium.
12/30 Chelsea 1 West Brom 0
Diego Costa nets the only goal in the 76th minute against a stubborn Baggies side.
13/30 Sunderland 0 Chelsea 1
Cesc Fabregas gets the breakthrough at the Stadium of Light just before half-time.
14/30 Crystal Palace 0 Chelsea 1
Diego Costa heads in the winner to secure another narrow victory for the Premier League leaders.
15/30 Chelsea 3 Bournemouth 0
The Blues secure a comfortable win over the Cherries at Stamford Bridge on Boxing Day.
16/30 Chelsea 4 Stoke 2
After a run of clean sheets, New Year’s Eve sees Antonio Conte’s side let in two at Stamford Bridge.
17/30 Leicester 0 Chelsea 3
Marcos Alonso celebrates his brace at the King Power Stadium.
18/30 Chelsea 2 Hull 0
Gary Cahill adds gloss onto another win in west London.
19/30 Chelsea 3 Arsenal 1
Marcos Alonso opens the scoring in the London derby before Eden Hazard and Cesc Fabregas add further goals.
20/30 Chelsea 3 Swansea 1
The Blues survive a scare following Fernando Llorente’s equaliser by beating the Swans.
21/30 West Ham 1 Chelsea 2
Antonio Conte’s side exact revenge on the Hammers for their EFL Cup win at the London Stadium earlier in the season by beating them in east London.
West Ham United via Getty Images
22/30 Stoke 1 Chelsea 2
Willian and Gary Cahill are on target as the Blues leave it until the 87th minute to beat the Potters.
23/30 Chelsea 2 Manchester City 1
Antonio Conte’s side react to losing to Crystal Palace at Stamford Bridge by seeing off Pep Guardiola’s side.
24/30 Bournemouth 1 Chelsea 3
Marcos Alonso nets another goal at the Vitality Stadium.
25/30 Chelsea 4 Southampton 2
Diego Costa bags a brace as the Blues march toward the title.
26/30 Everton 0 Chelsea 3
In what is seen as a big test of their title credentials, the Blues win at Goodison Park thanks to Pedro’s stunning opener.
27/30 Chelsea 3 Middlesbrough:
The hosts condemn Boro to relegation as they move to within one win of the title.
28/30 West Brom 0 Chelsea 1
Michy Batshuayi’s 82nd-minute winner hands Antonio Conte’s side the Premier League title.
29/30 Chelsea 4 Watford 3
Despite a much-changed line-up, the Blues see off the Hornets in a seven-goal thriller.
30/30 Chelsea 5 Sunderland 1
Stamford Bridge said farewell to John Terry as Chelsea finished the season in style.
“I had no doubts about it from the very first moment the coach told me he wanted me to play there.
“I thought I was capable of doing it and I’m always trying to improve and take in advice to keep on developing as a player.
“It’s important to have that flexibility and be ready for it, because the coach can choose between different systems depending on our opponents. So it’s important to have confidence in order to be able to swap systems.”
He added: “In a three-man defence you get more in touch with the ball and you participate more when distributing it. The way you attack is different too, because when you play as a full-back you do so in wide areas. You can cross the ball from closer to the box.”