Tian-Lang, who at 13 years and 173 days became the European Tour's youngest-ever player when he teed off, would go on to encounter a baptism of fire following two bogeys and one double bogey in his first five holes.
The teenager would settle in somewhat for the remainder of his round, finishing just one further shot over par 13 holes later.
Guan had finished fourth in a qualfying event for the right to play at the event on home soil, took the age record from fellow Chinese golfer Lo Shik-kai's feat at the 2003 Hong Kong Open.
Baldwin, meanwhile, went entirely bogey-free to lead the early going with Joost Luiten, Fredrik Andersson-Hed, Jean-Baptiste Gonnet, Scott Strange and another Englishman in Gary Boyd all one shot behind the 26-year-old.
'It was very good today so I am happy with that,' Baldwin told the European Tour's website.
'My caddie and I set out this morning with a game play of trying to make 18 pars and take our chances when they came, and it turned out to be one of those days where there were a lot of chances and I managed to take a few of them.'
Colin Montgomerie's 68 put him three strokes behind Baldwin, while Graeme Storm made it a hat-trick of English front-runners amidst a number of players to register a 67.
Paul Casey matched Monty with a four-under 68, while Simon Dyson also finished the opening round under par by a single stroke with a 71.