Baseline Buzz: Djoker, Fed ready

— -- LONDON -- This Wimbledon feels like a game-changer.

Grigor Dimitrov bounced defending champion  Andy Murray in the quarterfinals , while Milos Raonic pounded Nick Kyrgios , an Australian teenager who stunned Rafael Nadal in the fourth round.

Thus, Dimitrov and Raonic -- both 23-year-olds and children of the '90s -- find themselves in their first Grand Slam semifinals against No. 1 seed Novak Djokovic and No. 4 Roger Federer, respectively.

"I guess that you can't really outrun time in one way," Raonic observed. "New guys got to come up, and they've got to step up. We've been doing better and better, especially throughout this year.

"It's good to be a part of it. It's nice to see that sort of human side to those four guys when you have to step up to face them. Have a belief more so than ever that it's yours for the taking if you play well."

The British oddsmakers aren't feeling this youth movement; Djokovic is the current favorite at 8-11, followed by Federer at 5-2 and Dimitrov and Raonic at 7-1.

Our tennis analysts aren't so sure. FiveThirtyEight's Carl Bialik and ESPN.com's Matt Wilansky and Greg Garber trade Baseline Buzz volleys on the subject of Friday's men's semifinals at the All England Club.

Garber: It isn't exactly 2001 again, but the aces have been flying. Raonic has 147 in five matches, followed by Kyrgios (128). John Isner had 108 in only three matches and Marin Cilic 108 in five. When Federer meets Raonic, how important will those 30-odd aces be for Raonic?

Bialik: They'll be vital, sure, but what impresses me even more about Raonic is what has happened when he's landed a first serve and it hasn't been an ace: He still has won 77 percent of those points. That's much better than Isner and Kyrgios, who were below 70 percent, and Cilic, at 74 percent. So even when Federer gets a racket on a Raonic bomb, he'll be on the defensive. Then again, Federer is no serving slouch, either; he has just 63 aces but has won 78 percent of the time with his non-ace first serves. And he has won a whopping 68 percent of his second-serve points, even better than Raonic's 66 percent. If those numbers make your eyes glaze over, here are just two to focus on: 7 and 6. Expect at least a couple of tiebreaker sets when these two master servers with shaky returns face off. Federer won't mind being aced a lot; he just needs a double fault, a lucky net cord or a shanked volley to win a tiebreaker.

Wilansky: Tiebreakers here have become a central theme. Stan Wawrinka and Feliciano Lopez played the 100th tiebreaker at Wimbledon this season -- the first time in the history of Grand Slam play that's happened. (The record was 97 here four years ago.) And that was two rounds ago. Federer, for what it's worth, has been broken just once so far. But what concerns me, especially if you're a Federer fan, is the poise Raonic has shown. Unlike Dimitrov and even Kyrgios, who have garnered a lot of headlines, Raonic is flying wildly under the radar, which is probably the way he likes it. And this from a guy who had three career Wimbledon match wins heading into this season.

Garber: There's a lot to like about both these matchups, but I'll be keying in on the Federer-Raonic match. This is a classic spring/autumn encounter, the kind that Federer used to dominate. One of the storylines coming in was whether the 17-time Grand Slam champion might add to that total here. The consensus was that this might be his last decent chance. Some things had to happen for him, and they have. Now he won't have to beat Nadal or Murray on his way to the title. Raonic -- and a depleted Djokovic -- just might do the trick.

Bialik: Federer relishes these matchups with younger generations, partly because he usually wins them but also because of his appreciation for the sport's history. He speaks often with fondness about his 2001 win here over Pete Sampras, the only time they played an official match as opponents. Federer would sound egotistical when he says he'd like to give younger players the chance for a similar match, if it weren't true that they also want the chance to play him while he's still near his best. So tennis historians should hope for a Federer-Dimitrov final. Raonic and Djokovic won't agree, but they and Dimitrov should have many more chances to play one another in Slam semis and finals. Can Dimitrov get to the final? I think he will if he plays as intelligently and ably as he did against Murray.

Wilansky: Dimitrov, like Federer, came into Wimbledon fresh off a grass-court tuneup win. He's riding a nine-match winning streak, and on Monday he will move into the top 10 in the official rankings. More than anything, though, we've seen the maturation of a Bulgarian star once known for wearing his party hat into the wee hours of the morning. Times have changed. The other day, he was sitting by himself in a local restaurant with only a smoothie and smartphone in hand. No entourage, no distractions. A year ago, the biggest headline Dimitrov made came via Serena Williams when she said he was a man with a "black heart." But he has really settled down, and if I had to pick one of these 23-year-olds to pull off an upset, it would be Dimitrov -- especially because Djokovic's form was a bit spotty in his last match against Cilic.

Garber: That's interesting because you picked Djokovic to win here, Mr. Tennis Editor. You also picked him to win the French Open -- as did I -- and how did that work out? These days, he's in an interesting place. When I saw him thump Nadal in the final at Miami, I thought he might give him a go at Roland Garros. When he drilled Nadal in the last two sets in Rome, I knew he was going to win in Paris. And then, although he said winning the French was his priority for the 2014 season, Djokovic came up woefully short in the final. Now he's slipping and sliding all over the place, like a cow on ice. Not quite sure what to make of his match with Dimitrov. I will yield to our numbers cruncher ...

Bialik: My formula requires the exact ingredients of Dimitrov's smoothie, and without that I can't compute his chances. The other numbers say this is Djokovic's match to lose: He's vastly more experienced than Dimitrov and has won this tournament before. Djokovic also has reached the final two of the past three years, and he would regain the No. 1 ranking if he wins. But on form and Wimbledon experience, Murray was the favorite against Dimitrov in the previous round, and we saw how that turned out. I'll be watching their backhand exchanges with interest. Murray and Djokovic probably have the best backhands in the world, yet Dimitrov seemed to get the better of Murray in those rallies. Wawrinka and his one-handed backhand have flummoxed Djokovic in recent Grand Slam encounters. If I were Dimitrov, I'd be watching video of those matches -- and Federer's defeat of Djokovic here two years ago -- instead of the women's semis on Thursday.

Wilansky: With his girlfriend, Maria Sharapova, out of the tournament, I am not sure how much interest Dimitrov has anyway. The Ladbrokes odds sound about right, but I'll go with Dimitrov and Raonic in a changing-of-the-guard day at the All England Club.