"I believe in Arsenal. We can achieve big things together. We have something exciting here and I believe the best is yet to come," he added.
The 20-year-old Duplantis, who set the world record of 6.18m on the World Indoor Tour in February, secured his victory after clearing 5.85m with his second attempt. He went on to clear 6.00m and finally conquered 6.15m with his second effort of the day.
Mateusz Klich reestablished Leeds' advantage from the spot in the 41st minute and the home side looked to be cruising after further goals from Patrick Bamford and a second from Helder, before further goals from Bobby Decordova-Reid and Mitrovic gave Leeds a nervy last 25 minutes.
Tottenham Hotspur began their season with a defeat, going down 1-0 at home to a James Rodriguez-inspired Everton.
Koeman also insisted he had a good relationship with Lionel Messi, after the striker had told the club he wanted to leave, only to later say he would stay in order to avoid lengthy legal wrangling.
The decision to declare Gor Mahia the 2019-20 champions in March with nine games of the season left due to the outbreak of the pandemic was upheld by a local tribunal on Tuesday.
"I spoke to him yesterday (Friday) before training; I think that the young players have to play regularly and that is what I told him," Koeman commented, adding that the same went for Carles Alena and new signing Pedri.
Tan sealed the win for Changchun with a drive in the 81st minute.
When asked about Suarez, who was also left out of a friendly against Gimnastic Tarragona at the weekend, Koeman said he had "spoken to him about the future and whether or not he will stay."
With just four minutes to go, Al-Ahli found a breakthrough as former Chelsea winger Marin drove into the heart of the Al-Shorta defense, and after a quick one-two with Abdulrahman Ghareeb, the German kept his composure to slot home from six yards.
In men's 5,000m, Duo Bujie became front runner from halfway, but he was overtaken with two laps to go. On the final lap, Peng Jianhua emerged to win with 14:13.78, Qin Zhenfei and Zhao Changhong finished second and third respectively, Duo Bujie missed the podium with the fourth place.