The South Korean coach was speaking after the derby match between Hanoi and Viettel FC on Monday, which was probably Hai’s final appearance for the club.
After the 1-0 victory for the home side, coach Chun said: "I have enjoyed working with Hai.
"It's unfortunate that he didn't renew his contract with the team, but it's good for him. After he leaves, we have two months left to work with the rest of the players to find the best solutions.
“In my opinion, no one in the V.League 1 can replace him now."
After months of speculation, Hai decided to cut ties with Hanoi FC to seek new opportunities playing abroad.
He will leave the club on April 12, when his contract ends, and although his team face the People’s Police in the qualifying round of National Cup on April 7, the midfielder is unlikely to feature.
Hai couldn’t mark his last appearance with a goal, but helped his side to victory thanks to a strike by Truong Van Thai Quy in the 61st minute.
After the match, Hai went to the stands to thank the fans and threw his shirt to supporters.
"This was a difficult match for Hanoi,” Hai said.
“The most important thing is that the whole team fought until the last minute and won three points.
“This was my last match in the V.League 1 and I can think of nothing better than winning three points.
“This win is dedicated to the fans. I hope they will always support the club in the future.”
In response to Hai’s affection, the fans chanted his name after the match.
He added: "I am very touched. I thank the fans who have always given me support and encouragement.
“Today, I have to also thank my teammates. Under any circumstances, we still work together to get the victory.
"In the past two years, Hanoi has not had the best results, but I think Hanoi is a team with strong traditions.
“When the confidence returns, they will take a worthy position with what they have built in the past. Motivation from the fans will help the team."
The midfielder was keeping tight-lipped about where he will next play.
He said: "Any player wants to adapt and integrate well with the new team. I hope I adapt quickly to develop in the right direction. I have to prepare a lot for the next journey, but this is a good time to show my ability."
Hanoi FC chairman, Do Quang Hien said: "I always wish Hai success. He will always be a footballer of Hanoi. Wherever he goes, there will be victory. Come back with victory, no worries."
One possible destination for the midfielder could be France, after he agent hinted he could be moving to Paris.
Source: Vietnam News