With Chelsea playing on consecutive days, Alonso made wholesale changes to the team that defeated AC Milan 3-0 in Jakarta on Saturday.
Delap, who joined Chelsea from Ipswich in 2025, had endured a difficult first season at Stamford Bridge, scoring just two goals in 41 appearances across all competitions.
The 23-year-old matched that entire tally against the Malaysian champions, with both goals coming from the penalty spot.
Johor Darul Ta’zim took an early lead through Arif Aiman before Delap converted two penalties to put Chelsea ahead.
However, the Blues were unable to hold on to their advantage. Robert Sánchez was beaten by a deflected Oscar Arribas free-kick in the 65th minute before Bergson restored the hosts’ lead four minutes from full time.
Chelsea eventually found an equaliser in the 89th minute when Antonio Glauder headed into his own net from a Mikhailo Mudryk cross.
The game was expected to proceed to a penalty shootout, but the players did not return to the pitch at Stadium Sultan Ibrahim Larkin.
Chelsea will now return to London before completing their pre-season preparations against Real Sociedad at Stamford Bridge on Saturday, 15 August.
