Djokovic once again comes through at crunch time

— -- Novak Djokovic doesn't soar into the Saturday semifinals of the ATP's year-end event with the massive momentum he might have imagined. But he'll take it.

After a fairly routine 6-3, 7-5 victory over No. 6 seed Tomas Berdych on Friday, Djokovic finished the round-robin phase at 2-1 and is the second-place finisher in Group Stan Smith.

Heading into what will be a heavily anticipated match with Rafael Nadal, the world No. 1 will have to settle for winning 24 of his past 25 matches in 2015 -- and 16 of the previous 17 at the Barclays ATP World Tour Finals.

Following his first loss since Aug. 23 to Roger Federer, Djokovic took care of his business, breaking Berdych at 5-all in the second set, two points after racing out to a love-40 lead. This one wasn't really in doubt; Djokovic is now 21-2 versus Berdych -- and a perfect 18-0 on hard courts.

Djokovic trails his career head-to-head series with Nadal by the slightest of margins, 23-22, but has won all three of their meetings in 2015 -- and all seven sets. Most notably, the 28-year-old Serb took Rafa out in the quarterfinals at Roland Garros and just last month in the Beijing final, 6-2, 6-2.

"[Nadal has] been playing better and he's been raising his level ever since US Open, I think," Djokovic told the press afterward. "Already in China, playing finals in Beijing, semifinals in Shanghai, you can feel that he's starting to get comfortable on the court, start to play better.

"The couple of matches, first couple of matches he played here against Wawrinka and Murray showed that, showed that he feels more confident, shows that he's starting to miss less, serve efficiently, use his forehand much better."

A Swiss miss

It required three sturdy sets -- and two hours, 10 minutes -- but Roger Federer dodged an important obstacle by defeating Kei Nishikori 7-5, 4-6, 6-4.

At least temporarily.

Federer avoided a semifinal showdown with the player who, in the course of a glorious career, has consistently gotten the better of him in Nadal.

The 34-year-old champion struggled early (he was within two points of a 5-3 deficit in the first set), but completed the round-robin portion of the event 3-0.

As the top finisher in the Group Stan Smith, Federer will play the second-place finisher in the other singles group, the winner of Friday's Andy Murray- Stan Wawrinka match. This is important because Federer's combined record against Murray and Wawrinka is a sparkling 31-14. Against Nadal, Federer is a dubious 11-23.

After the match, Federer claimed to have no preference who he plays Saturday.

"OK, maybe for [Nadal's] standard, it's not the best season," Federer said to the press. "What is he going to finish, top five? It's still a good season. Everybody would take it almost except maybe a few players at this tournament.

"I think he's going to get stronger. In the backhand he showed what's to come in '16, in my opinion. Then with some time to practice and reassess his game, he's going to be tough to beat in Australia. I believe that.

"Of course, he can win the tournament here after his convincing wins against Murray and Stan."

Bryan brothers survive

With No. 1 seeds Bob and Mike Bryan two points from extinction, the O2 crowd got behind Jamie Murray, brother of Andy Murray and the pride of Great Britain, and partner John Peers. But the wily 37-year-old California twins won the last four points of the second-set tiebreaker and went on to prevail in a wild match, 6-7 (5), 7-6 (5), 16-14. Thus, they advance to Saturday's semifinals against the winner of the Group Fleming/McEnroe, either No. 2 seeds Jean-Julien Rojer and Horia Tecau or No. 6 Pierre-Hugues Herbert and Nicolas Mahut.

Two of those crucial four points came against the serve of Peers, who tightened noticeably as the points grew in importance. With the score 14-all in the final frame, Peers couldn't land a blistering volley and Mike Bryan stroked a service winner to complete the escape.

How close was it? The Bryans won 92 points, one more than their opponents.

The most decorated team in men's doubles history is seeking an 11th year-end No. 1 ranking.

On tap for Friday

Last call before Saturday's semifinals.

Local favorite and No. 2 seed Murray must beat No. 4 Wawrinka to advance to the next round and place all of the Big Four in the final four. ( Watch on ESPN2 & WatchESPN, Friday, 3 p.m. ET.)

Surprisingly, Murray holds only an 8-6 career head-to-head edge, but Wawrinka won the past two matches -- back in 2013. With a win in the late match, Murray can guarantee he'll finish a best-ever, year-end No. 2.

No. 5-seeded Nadal, who has already locked up the No. 1 seed in Group Ilie Nastase, meets fellow Spaniard No. 7 David Ferrer. ( Watch on ESPN3, Friday, 9 a.m. ET.)

Three teams from Group Fleming/McEnroe are alive for final spot in the doubles semifinals: No. 3 Ivan Dodig and Marcelo Melo, No. 6  Herbert and  Mahut and No. 7 Marcin Matkowski and Nenad Zimonjic.

No. 2 seeds  Rojer and  Tecau are already in.