Port suffered their first defeat of the season when they went down 2-1 to BG Pathum United at home in a Thai League 1 clash on Sunday night.
Freddy Alvarez and Chanathip Songkrasin scored in the 14th and 56th minutes before Willen Mota pulled one back for Port in the final added time.
Chanathip, who was voted man of the match, said: "This match was important for us because we had not been able to produce the desired results in our previous games.
"But this is just one game, and it will mean nothing if we fail again in our next match.
"We played well tonight and showed everyone that we are capable of beating the top sides in the league."
Port coach Rangsan Viwatchaichok said: "I apologise to the Port fans that we could not pick up three points at our home ground.
"Since I have become the coach, we [Port] have never beaten Pathum United either in the league or the Cup competitions, so we wanted to win this match.
"The players put in their best effort tonight and fought till the last minute despite playing against Persib Bandung in an AFC Champions League Two game in the midweek."
Meanwhile defending champions Buriram United ran riot again to thrash PT Prachuap 6-0 on Sunday night.
Supachai Chaided (9), Pansa Hemviboon (14), Guiherme Bissoli (53), Theerathon Bunmathan (79), Jefferson Tabinas (86) and Chrigor scored for the Thunder Castle.
In another game on Sunday night, hosts Rayong lost 3-0 to ten-man Bangkok United.
The Angels scored through Muhsen Al-Ghassani (27), Mahmoud Eid (30) and Nitipong Selanon (45).
Bangkok United captain Everton Goncalves fouled Rayong striker Stalio Junior in the 76th minute and was sent off.
Freddy Alvarez and Chanathip Songkrasin scored in the 14th and 56th minutes before Willen Mota pulled one back for Port in the final added time.
Chanathip, who was voted man of the match, said: "This match was important for us because we had not been able to produce the desired results in our previous games.
"But this is just one game, and it will mean nothing if we fail again in our next match.
"We played well tonight and showed everyone that we are capable of beating the top sides in the league."
Port coach Rangsan Viwatchaichok said: "I apologise to the Port fans that we could not pick up three points at our home ground.
"Since I have become the coach, we [Port] have never beaten Pathum United either in the league or the Cup competitions, so we wanted to win this match.
"The players put in their best effort tonight and fought till the last minute despite playing against Persib Bandung in an AFC Champions League Two game in the midweek."
Meanwhile defending champions Buriram United ran riot again to thrash PT Prachuap 6-0 on Sunday night.
Supachai Chaided (9), Pansa Hemviboon (14), Guiherme Bissoli (53), Theerathon Bunmathan (79), Jefferson Tabinas (86) and Chrigor scored for the Thunder Castle.
In another game on Sunday night, hosts Rayong lost 3-0 to ten-man Bangkok United.
The Angels scored through Muhsen Al-Ghassani (27), Mahmoud Eid (30) and Nitipong Selanon (45).
Bangkok United captain Everton Goncalves fouled Rayong striker Stalio Junior in the 76th minute and was sent off.
