Since the Filipino-German declared his intent to represent his mother's country of birth back in 2019, Philippines have been eagerly awaiting to unleash the attacker -- currently plying his trade in the Bundesliga with Bochum - but it has been far from a smooth sailing process.
Initially, it took some time to get the necessary documentation sorted in order for Holtmann to gain Philippines citizenship. Then, earlier this year, just when it looked as though he would make his debut in the FAS Tri-Nations Series against Singapore and Malaysia, he contracted COVID-19 just before flying out to Southeast Asia.
But as the Azkals look to ignite their Asian Cup final-round qualifying campaign against Mongolia after a disappointing opening 0-0 draw with Yemen on Thursday, there is finally nothing stopping Holtmann from winning his first cap in Ulaanbaatar.
"Obviously, I'm as excited as the fans to play for Philippines," he told ESPN. "When you think of how many obstacles there have been, I'm even more honoured and excited to finally make my debut.
"I've been following nearly every match but this won't be a one-man show. I know people see the goal against Mainz (a stunning solo effort that won the 2021 Bundesliga Goal of the Year) and think I will do everything on my own, but I need my teammates.
"I've seen the quality we have in training, even if it's just been two sessions. I'll give everything to lift this team but I'll also be looking to my team for help."
Apart from that stunning effort against Mainz, Holtmann also scored another brilliant effort last season in Bochum's stunning 4-2 win over Bundesliga record champions Bayern Munich back in February, only leading to further excitement as to what a player of his calibre -- effectively a one-man highlights reel -- will bring not just to Philippines but all of Asian football.
While he has spent all his life in Germany, Holtmann has visited Philippines thrice previously, embraces the family values associated with the culture, and even humourously burst out with the words "chicken adobo" -- the famed dish -- when asked about how he relates to his Filipino identity.
Holtman could possibly have lined up for the Azkals even earlier than he is about to do so but made the decision to focus on first establishing himself at club level, although -- in a sign of his commitment now that he has been cleared to represent Philippines -- he flew out to Mongolia for the Asian Cup qualifiers just two days after his wedding.
"The whole process (of representing Philippines) started six years ago. Several coaches -- Scott Cooper, Sven-Goran Eriksson included -- approached me," the 27-year-old explained.
"I was still young and just on my way to try and become a regular starter in the Bundesliga. I didn't want to put more pressure on myself or affect my condition from all the travelling.
"Now what I've been a regular starter in the Bundesliga for the last one and a half years, I spoke to my mother and told her I wanted to play for Philippines and obviously she was very delighted."
Holtmann revealed that fellow Filipino-German and ex-Azkals captain Stephan Schrock -- not in the current side -- has been hugely supportive with advice.
It has also helped to have others of similar German-born-and-bred heritage like Patrick Reichelt and the Ott brother -- Manny and Mike -- in the team, although he communicates fluently enough in English to have integrated well with the entire squad.
Holtmann is also no stranger to Asian football, understandable given the plethora of the continent's stars that have made their way to the Bundesliga.
Having previously shared a dressing room with Yoshinori Muto at Mainz, Holtmann is also now Bochum teammates with another Japan star in Takuma Asano - two players he could find himself up against should Philippines qualify for a second consecutive Asian Cup.
Given the story of his international career seems to be one of making up for lost time, it is perhaps no surprise that Holtmann -- having failed to arrive in time for the opening stalemate with Yemen -- is simply raring to play his part for the Azkals as they look to build on their historic maiden appearance on Asia's biggest stage back in 2019.
"I'm really excited to have this aim," he added. "Three years ago, I saw how this was the biggest achievement of the Philippines national team.
"I'm extremely motivated for Philippines to do it for the second time -- with me now. To play in such a big tournament like the Asian Cup should be the aim for the future of Philippines."