WASHINGTON -- After making the postseason for the fifth time in eight years, the Nationals finally broke through on their ultimate goal and won the World Series.

The Nats have been one of baseball’s most successful teams since 2012, but winning the World Series still serves as validation for general manager Mike Rizzo and the organization. Now comes an even bigger challenge: trying to become the first team to repeat since the Yankees won three consecutive championships from 1998-2000.

In some ways it won’t be easy to do -- not with the oldest roster, the second-worst bullpen in baseball and two of their top stars set to hit free agency -- but the Nats still have a strong core of Juan Soto, Victor Robles, Max Scherzer and Patrick Corbin intact with hopes of keeping Anthony Rendon and Stephen Strasburg in D.C.

1. Will the Nationals re-sign Anthony Rendon?

Rendon will be the top position player available in free agency, and after a season worthy of consideration for the National League Most Valuable Player Award, most teams could upgrade at third base by signing him. Both he and the Nationals have repeated their interest in a reunion, but they were not able to get a deal done during the season. And now Rendon will hit the open market.

• Rendon's big offensive contributions help win World Series

The Nationals do not have Major League-ready prospects in their farm system to replace Rendon, like they did to replace Bryce Harper in the outfield after his departure last season. So third base is perhaps their top priority this offseason.

2. Will Stephen Strasburg return in 2020?

Strasburg holds an opt-out clause this offseason that could put him in position to be one of the most attractive players on the market. And after watching the postseason, it’s clear just how crucial Strasburg and starting pitching is to the Nationals formula for success. So, even if Strasburg does plan to exercise his opt-out clause, the club seems likely to pursue a way to keep him in a Nationals uniform next season.

3. How will the Nationals improve their bullpen?

Washington was able to largely avoid the problem in the postseason, but its bullpen ranked 29th in MLB in ERA during the regular season, threatening to torpedo its success at any point. The Nationals cannot expect to repeat that formula and still repeat as champions, so they will have to seek more reliable relievers, especially considering Daniel Hudson is a free agent.

4. What happens with Ryan Zimmerman?

Zimmerman, 35, showed during the postseason he can still be a productive player if he’s healthy, but that is becoming a big if during the regular season. He played 52 games in 2019, the fewest of any full season in his career, and he has played more than 120 games once (2017) in the past six seasons. He’s only played more than 100 games in one additional season (2016) during that span. Zimmerman has expressed a desire to play for a few more years, and the Nationals want him back, even if they seem unlikely to accept an $18 million team option for 2020. Even with Zimmerman back, however, the Nationals will need to find someone to help complement him at first base as they have in recent years.

5. Who plays second base?

Howie Kendrick is headed for free agency along with Brian Dozier, so the Nats are going to have to decide what to do at second base next year. Kendrick was their NLCS MVP and hit two of the biggest homers in team history in Game 5 of the NLDS and Game 7 of the World Series, but he will also turn 37 next summer and is likely better suited to be a designated hitter at this stage of his career. The Nats could decide top prospect Carter Kieboom is ready for the big leagues full time despite struggling in his brief big league stint last year.