Alonso, who officially took charge on July 1, watched his side recover from falling behind three different times before Pedro's late burst secured victory at Stadium Australia.

Chelsea, missing several senior stars on international duty, fielded a youthful starting line-up and spent the opening hour relying heavily on academy graduates and emerging talent.

The visitors made the perfect start when 17-year-old Kazakh forward Dastan Satpaev marked his debut with a goal after just six minutes. Ryan Kavuma-McQueen threaded a superb pass through the defence and Satpaev finished powerfully at the near post.

Western Sydney responded quickly, exposing Chelsea's defensive weaknesses. Anthony Pantazopoulos headed home from a corner before Aydan Hammond calmly finished another well-worked move to give the Australian side a 2-1 lead.

Chelsea levelled before half-time through Portugal Under-21 midfielder Dario Essugo. He combined neatly with Reggie Walsh in a clever one-two before guiding his finish into the far corner to make it 2-2.

The Wanderers regained the lead shortly after the break when Dylan Scicluna turned smartly inside the penalty area before finishing confidently to make it 3-2.

Alonso reacted immediately, making nine substitutions in the 62nd minute. The introduction of Cole Palmer and Pedro transformed Chelsea's attack, increasing the tempo and creating constant pressure on the hosts.

Although Western Sydney briefly restored their advantage at 4-3, Chelsea finished the match in emphatic fashion. Pedro took centre stage by scoring three goals in just nine minutes to complete his hat-trick and inspire the Premier League side to a thrilling 6-4 victory.

The result gives Alonso an encouraging start as he begins rebuilding Chelsea following last season's disappointing 10th-place Premier League finish, which saw the club miss out on European football.

Chelsea have already strengthened their squad with the arrivals of Morgan Rogers, Geovany Quenda, Marco Palestra and Emmanuel Emegha during the summer transfer window. Only Palestra is part of the current pre-season tour, while several key internationals, including Reece James and Enzo Fernandez, remain unavailable after their World Cup commitments.

Chelsea's preparations step up on Saturday when they face London rivals Tottenham Hotspur in Sydney before continuing their pre-season tour with matches in Hong Kong, Indonesia and Malaysia.

Brandon Petersen: It is very important to keep the ball rolling