Trentin was comfortably the quickest in the uphill sprint in Alhaurín de la Torre, springing clear inside the final few hundred metres and crossing the line with enough of a margin to sit up and celebrate.
It is the Australian team's eleventh win of the 2019 season, and Trentin's second of the week, following his success on stage two.
The win for Astana's Danish rider Fugslang came courtesy of a second-placed finish on stages one and three and finishing in the chasing group on stage four when Simon Yates won via a memorable attack and previous race leader Tim Wellens was unable to keep pace. It's Fugslang's first GC success since the Critérium du Dauphiné in 2017.
How it happened
The day's race began in the starting town of Otura but it took more than 10km for a breakaway to form, which notably included the previous day's stage winner Yates.
The group swelled to nine from five, but after some chasing from the peloton, the escapees finally settled on a four-man contingent of Yates, Tomasz Marczynski (Lotto-Soudal), Antwan Tolhoek (Jumbo-Visma), and Oscar Riesebeek (Roompot-Charles).
Tolhoek was seemingly placed in the break to assist teammate Steven Kruijswijk later on in the race should required, given that he was just 11 seconds off race leader Fugslang. Astana, however, responded by bringing the break back from four minutes to less than a minute's advantage with 44km remaining.
As the race reached the final climb, a short and sharp ramp up Alto del Valle de la Vida, Yates attacked his breakaway companions, springing clear immediately and stretching a lead of around 40 seconds to the peloton.
It briefly sparked hope among Mitchelton-Scott that Yates could win via a long distance attack for the second successive day, but he was reeled in. His capture, in the presence of Guillaume Martin (Wanty-Groupe Gobert) and Fausto Masnada (Androni Giocattoli-Sidermec), ignited the latter to go solo himself on the descent with 27km to go.
Despite Masnanda's efforts, he too was sucked back into an Astana-led bunch 10km later, setting up a sprint finish.
But the run-in, in spite of being flat, was far from straight-forward. Strong crosswinds stemmed the speed and resulted in the peloton shredding several riders. Petr Rikunov (Gaxprom-RusVelo) moved clear of the peloton temporarily but inside five kilometres until the finish the reduced bunch was one long line.
The inclination of the finishing straight lent itself to Trentin being touted as the favourite, and he was afforded a superb leadout from Esteban Chaves and Edoardo Affini.
When the road cranked up in gradient, European champion Trentin pushed on, darting to the left of the road. No one behind was able to follow the Italian's speed, and it was a case of determining the final podium spots, taken by Enrique Sanz (Euskadi Basque Country - Murias) in second and Carlos Barbero (Movistar) in third.
Ruta del Sol 2019, stage five Otura to Alhaurín de la Torre (163.9km)
1. Matteo Trentin (Ita) Mitchelton-Scott, in 3-58-19
2. Enrique Sanz (Esp) Euskadi Basque Country - Murias
3. Carlos Barbero (Esp) Movistar
4. Tosh van der Sande (Bel) Lotto-Soudal
5. Colin Joyce (USA) Rally UHC Cycling
6. Matej Mohorič (Svn) Bahrain-Merida
7. Juan José Lobato (Esp) Nippo Vini Fantini Faizanè
8. Lars Boom (Ned) Roompot-Charles)
9. Eduard Prades (Esp) Movistar
10. Steven Kruijswijk (Ned) Jumbo-Visma, all at same time
General classification after stage five
1. Jakob Fuglsang (Den) Astana, at 17-42-00
2. Ion Izagirre (Esp) Astana, at 7secs
3. Steven Kruijswik (Ned) Jumbo-Visma, at 11secs
4. Pello Bilbao (Esp) Astana, at 21secs
5. Adam Yates (GBr) Mitchelton-Scott, at 57secs
6. Jack Haig (Aus) Mitchelton-Scott, at 1-08
7. Sergio Higuita (Col) Fundacion-Euskadi, at 1-12
8. Aleksandr Vlasov (Rus) Gazprom-RusVelo, at 1-43
9. Tim Wellens (Bel) Lotto-Soudal, at 2-53
10. Dylan Teuns (Bel) Bahrain-Merida, at 3-41
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