Alexander Zverev's long-predicted arrival at the summit of men's tennis is taking too long for some impatient observers but he took another significant step forward by beating John Isner to reach the last four at the ATP Finals on Friday. His 7-6(5) 6-3 victory over the American meant the 21-year-old became the first German since Rainer Schuettler in 2003 to reach the semi-finals of the prestigious year-ending tournament and the youngest since Argentine Juan Martin del Potro in 2009. Zverev's second group victory earned him the runner-up spot behind world number one Novak Djokovic and he will now aim his range of baseline weapons at six-times champion Roger Federer in a Saturday afternoon clash of the generations. “It's obviously great getting to the semi-finals. But the tournament isn't over,” Zverev, 21, said. “There's only good opponents left. There's only the best in the world. “I don't want to really be thinking about ‘I'm in the semi-finals now, I'm satisfied'. That's not how I work.” The other semi-final will be between five-times champion Djokovic, who beat Zverev comfortably earlier this week, and South African debutant Kevin Anderson. Djokovic completed group play later on Friday when he beat Marin Cilic 7-6(7) 6-2 in a dead rubber to stay on course for the $2.7 million on offer for an undefeated champion. Not easing up despite having sealed top spot in the group, Djokovic won 31 consecutive points on serve during the match. Real Contender While not a Grand Slam tournament — in which Zverev has yet to go beyond the quarter-final stage — the ATP Finals are regarded in some quarters as a ‘fifth' major. The floppy-haired, gold chain-wearing Zverev looked every bit a real contender for the game's biggest prizes as he fired down 140mph serves and thrilled the packed crowd with spectacular groundstrokes, especially from his lethal backhand. One Hollywood effort early in the second set, struck for a clean winner from almost in the front row seats, revealed the showman in Zverev as he conducted the rapturous applause. There have been questions about his mental toughness including last year here in London when a loss to Jack Sock cost him a semi-final berth and this year at the Australian Open when, seeded four, he lost the fifth set of a third-round clash against fellow young gun Chung Hyeon 6-0. But with Andy Murray's former coach Ivan Lendl and strength conditioner Jez Green now in his team, Zverev, younger brother of experienced Tour player Mischa, appears to have developed a tougher streak to handle the big moments. He faced a set point at 5-6 in the first set and survived it with a massive ace. Then, at 5-5 in the tiebreak with Isner throwing the kitchen sink at a return, he produced a superbly improvised shot, played on the half-volley from almost under his feet on the baseline, to catch his opponent by surprise. Isner, whose hopes of reaching the semi-finals required a straight-sets win and a Djokovic victory over Cilic, netted a forehand to drop the set and there was only ever likely to be one outcome after that. Despite knowing his hopes were over, Isner remained competitive in the second set until dropping serve in the eighth game — the only break in a match of high-quality serving. “If Sascha serves like that, he could have a very good shot at winning (against Federer),” Isner said. “I do believe it will be a very close match tomorrow between those two.” Zverev last played Federer a year ago, losing in three sets at the O2 Arena, while Djokovic has beaten Anderson twice this year, most notably in the Wimbledon final — since when the Serb has been almost unbeatable, winning 34 of his last 36 matches.
