1.  Novak Djokovic – I am sure Nole would have loved to have grabbed the big trophies in Paris and London to end the year.  Still, his Wimbledon and US Open triumphs as well as solving the riddle of Cincinnati more than place him atop men’s tennis for 2018.   On the plus side, finishing the year with two near misses may leave Novak chomping at the bit for a 7th Australian Open title.
2. __________________ – There is space for someone to challenge Djokovic in a robust manner in 2019.  The question is who?  Sascha Zverev certainly has momentum and a coach with results.  Roger Federer was much closer to Djokovic in Paris than he was in Cincinnati.  Rafael Nadal can build a strong season, but he has health issues lingering.  Juan Martin del Potro is limited on his backhand wing these days and is rehabbing yet another injury.  Karen Krachanov, Stefanos Tsitsipas, and others are worth watching, but there is no clear #2 at the moment heading into 2019.
3. Sascha Zverev – Based on momentum heading into the new year, Zverev has to be near the top of this power ranking.  Ivan Lendl may bring the last touches needed to push the talented and scattered star to new levels.
4. Roger Federer – Federer skipped the entire clay court season and had a disappointing US Open.  Still, at 37 he enters 2019 knowing that he can win big prizes if his health is there and a break or two comes his way.  Many other players wonder if they can break through so he is in an enviable spot as compared to many ATP players.
5. Rafael Nadal – From the start of the Australian Open through Day 1 of the US Open, Nadal had the best year on tour.  Much of this was built on clay court dominance, but Rafa was as close as he has been to winning Wimbledon in years.  He also grabbed a big title in Canada.  If Nadal is healthy, he and Djokovic could have some wars in 2019.  I am not sure how much momentum or confidence Rafa will have at the start of 2019 though.   Since power rankings tend to focus as much on now as on a body of work Rafa is #2 for 2018 but #5 in terms of momentum heading into next year.
6. Kevin Anderson ***- Anderson reached his second major final while also grabbing a few wins along the way.  Anderson has a huge serve, is professional in terms of maximizing fitness and preparation, plays with tactical discipline, and has a strong will when competing.  He’d also likely admit that his game is not quite as fluid as those ranked ahead of him on this list.
7. Dominic Thiem – He ended his World Tour Finals round-robin play on a high note by beating Kei Nishikori.  A 2018 Roland Garros runner-up finish, as well as his near miss vs. Rafa in New York, give Thiem plenty of reasons to smile as he enters 2019.
8. Marin Cilic – The big man can still add to his 2018 by helping Croatia grab a Davis Cup title.  Croatia was close when it lost 3-2 to Argentina in the 2016 Davis Cup final.  Cilic has reached 3 major finals in his career and has a game that has placed him in many second week situations at majors.  Things may need to break his way to win a second major in 2019, but Cilic is one of the few people who can realistically win a major next year.  A 2018 Davis Cup title might spur him on to a big 2019.
9. Stefanos Tsitsipas – He has a lot of game and won the NextGen title.  Momentum will be with him as 2019 commences.
10. John Isner – The big man won Miami and came within a game of reaching the 2018 Wimbledon final.  His approach to matches is pretty simple, but it proved to be effective enough to be in the mix at multiple big events.

*** Juan Martin del Potro would be in this list if he were not recovering from a pretty serious injury.  He’d be no lower than 6th.  He reached the final 4 at Roland Garros, the final 8 at Wimbledon, and the championship match at the US Open on top of taking the 2018 Indian Wells title after fending off match points.