The 26-year-old is currently ranked six after two tournament wins in 2024 at Geneva and Barcelona.
He surged to a career-high two in 2022 when he made the French and US Open finals.
"If you end the year top 10 it's been a good year, but I think that top five is also doable, reachable definitely," he said in Sydney at the United Cup when asked about his 2025 goals.
"If you look at the players, in my eyes Jannik and Carlos had two phenomenal years, both of them.
"Those two are what most people are looking to and referring to these days. They will be tough to handle, but other than that, I think it's open for changes in the top five."
Sinner is currently world number one by more than 3,000 ranking points from Alexander Zverev, with Alcaraz three, Taylor Fritz four and Daniil Medvedev five.
"Everyone is competitive," said Ruud.
"I think I showed last year, especially the beginning, that if I'm playing well I can be in a position to take a few more steps. I've been there before. So that's something that is a high goal."
Playing better at Grand Slams is also on his agenda after an underwhelming 2024 at the majors with a semi-final appearance at the French Open his highlight.
"Last season was good in some ways, but, for example, here in Australia I felt like I could have done better, and Wimbledon especially also," he said.
"A few maybe better and deeper runs in Grand Slams is one goal for this year."
