The spring clay season takes a hard turn in this weekend's Fed Cup semifinals.

Defending Fed Cup champion Italy visits the Czech Republic in a meeting of nations that have combined to win the last five competitions. Across the globe, Australia hosts Germany in a tie of two teams aiming for their first Fed Cup final appearance in more than two decades. Which two teams will secure a spot in the November final?

*Hard Court

CEZ Arena Ostrava, Czech Republic  
Head-to-head: Italy leads 5-4*

Why Italy will win

The reigning champion has beaten the Czech Republic in two of their last three semifinal meetings and is strengthened by the return of veterans Sara Errani and Roberta Vinci, who sat out Italy's 3-1 quarterfinal victory over the United States. Karin Knapp scored two singles wins in the quarters. Rising world No. 54 Camila Giorgi has won nine of her last 12 matches, including victories over world No. 5 Maria Sharapova and Andrea Petkovic, and should be sharp from reaching her first WTA final in Katowice last weekend. Though the 31-year-old Vinci is slumping badly, her slice backhand and ability to change the pace has short-circuited Czech power players in the past: She has won two of three meetings with Czech No. 1 Petra Kvitova and is 4-2 lifetime vs. No. 2 Lucie Safarova.

Why Czech Republic will win

The fast track suits the home team's flatter hitters: The Czechs have not lost a home tie since 2009. Former Wimbledon winner Kvitova can be both explosive and erratic—sometimes in the space of a single game—but she's the purest ball striker and most dangerous player in this tie, plays her best tennis indoors (17-3 in Fed Cup matches under the roof), and is inspired in Fed Cup competition. Kvitova has won 14 of her last 16 Fed Cup matches and is 6-0 lifetime against Italian No. 1 Errani, while Vinci has looked haunted in a ghastly 2-9 start to the season. Czech No. 3 Klara Koukalova has won more singles matches this year (20-10) than any woman in this tie, and while Safarova is 10-11 lifetime in Fed Cup—including losses to Errani and Vinci in the 2013 semifinals on red clay in Palermo—she's riding a four-match winning streak at home.

X-Factor

Should doubles decide it, both nations boast accomplished options. Andrea Hlavackova is the defending U.S. Open doubles and mixed doubles champion and reached the Australian Open quarterfinals partnering Safarova. Former world No. 1 doubles team Errani and Vinci are the reigning Australian Open champions and Vinci has been unbeatable in Fed Cup doubles: She holds an 18-0 record—the most doubles wins without a loss in Fed Cup history. The last time the Czech Republic lost a home tie, the American pair of Liezel Huber and Bethanie Mattek-Sands scored a three-set doubles win to clinch a 3-2 victory in the 2009 semifinals.

The Italians are tournament tough, winning three of the last five Fed Cup championships, but the home team has won the last three semifinal meetings between these nations—and gone on to claim the Cup. Kvitova is a commanding Fed Cup player and the Czechs are the deeper team that should advance to their third final in the last four years.

*Hard Court

Queensland Tennis Centre, Brisbane, Australia  
Head-to-head: Australia leads 8-4*  

Why Germany will win

A potent cast and productive form favors the Germans. A spirited Andrea Petkovic will be empowered by winning the biggest title of her career in Charleston two weeks ago. German No. 1 Angelique Kerber has reached two hard-court finals this year—Sydney and Doha—and plays a grinding game that can extract errors and exact a physical toll on opponents. Both women are better movers than the likely Aussie singles starters and both have been opportunistic on return this year: 2011 Brisbane finalist Petkovic has won 46 percent of return games played; Kerber 40 percent. Australian No. 1 Samantha Stosur has not won back-to-back matches since February, she is 1-3 lifetime against Germany's Julia Goerges, and is prone to playing nervous, tentative tennis on home soil. If the Germans can jump out to an early lead, they can pose psychological pressure on the home side, aiming for its first Fed Cup championship in 40 years.

Why Australia will win

Though Stosur can be skittish at home, she's stepped up in team competition, winning eight of her last 10 Fed Cup singles matches. The 2011 U.S. Open champion possesses the hellacious kick serve and massive forehand to dictate play: Stosur scored straight-sets wins over Kerber and Petkovic leading the green-and-gold to a 3-2 victory in the 2012 Fed Cup Playoffs on red clay in Stuttgart. Australian No. 2 Casey Dellacqua has been resurgent, working her lefty spin shrewdly in winning 12 of her last 15 matches. Former world No. 1 doubles player Stosur is 6-0 lifetime in Fed Cup doubles. Both Dellacqua, 7-1 in Fed Cup doubles matches on hard courts, and Ashleigh Barty are Top 20-ranked doubles players, who joined forces to reach three Grand Slam doubles finals last year (Australian Open, Wimbledon and U.S. Open).

X-Factor

Nerves. Two traditional tennis powers have a lot on the line: Germany is driven to reach its first Fed Cup final since 1992, when Steffi Graf and Anke Huber clinched the Cup. Seven-time champion Australia is playing for its first final appearance since 1993. How will the players respond to the pressure? Playing on Pat Rafter Arena should help the Aussies, particularly if doubles decides it. But Germany has won four of its last five road ties and the visitor has won at least one of the Fed Cup semifinals in seven of the last 10 years.

Germany is superior in singles, Australia is stronger in doubles. The 19th-ranked Stosur is slumping—she has not beaten a Top 20 player since last October  and often looks stressed out on home soil—while the 28th-ranked Petkovic is streaking. And stubborn Kerber is always tough out. Still, if Stosur, Australia's all-time Fed Cup singles victory leader, can assert her game and make doubles matter, the Aussies can squeeze out a demanding home victory.