ROME - Novak Djokovic battled into the Rome Masters final on Saturday after coming through a tough semi-final with Milos Raonic to beat the Canadian 6-7 (5/7), 7-6 (7/4), 6-3. Defending women's champion Serena Williams, meanwhile, secured her place in Sunday's final against Italian Sara Errani after beating Serbian 11th seed Ana Ivanovic 6-1, 3-6, 6-1.Djokovic, the number two seed, will face world number one Rafael Nadal in Sunday's final should the Spaniard defeat Bulgaria's Grigor Dimitrov in the second semi-final. Djokovic had ousted David Ferrer 7-5, 4-6, 6-3 in the quarter-finals while Nadal came through a tough clash with British number one Andy Murray on Friday.But the world number two was stretched by the hard-hitting Raonic, whose serves were regularly coming in just under the 230 km/h mark. "I can't recall last time when I was feeling so helpless returning, even his second serves," said Djokovic. With only five career singles titles, Raonic admitted he was happy to have pushed Djokovic all the way. "He played better than me and he deserves to win," said the 23-year-old."I'll take a lot of positive things (from the match), and I am happy with it. I take what I have done here and try to do better at Roland Garros." The pair's only previous meeting came last year when Djokovic beat the Canadian 7-6 (7/1), 6-2, 6-2 in a Davis Cup semi-final rubber. A year on from that win, Raonic left a much bigger impression on the six-time Grand Slam champion."He did surprise me with his movement, especially given his size, and he's got variety in his shots. You could feel the improvement in his game," he added. Djokovic, who took exactly three hours to rack up his second win against Montenegrin-born Raonic in as many encounters, has won the Rome Masters twice, in 2008 and 2011. Nadal is in the hunt for an eighth win in the Italian capital but Djokovic hopes Saturday's tough work-out will stand him in good stead."It is a big win because it gives me a lot of strength and belief that I can carry into tomorrow's final, and also for the rest of season," added the 26-year-old. Overall, Djokovic has won 18 of his 40 previous encounters with Nadal, including the last three, although they all came on hard courts. Of the duo's 16 meetings on clay, Nadal has won 13 including their last meeting on the surface at the semi-finals of the French Open in 2013.Earlier, Errani booked her place in the women's final to maintain her hopes of becoming the first Italian woman to win the tournament in 29 years. Errani, seeded 10, upset China's number two seed Li Na 6-3, 4-6, 6-2 on Friday and ousted Serbian sixth seed Jelena Jankovic 6-3, 7-5 in their semi. "It was quite difficult out there, Sara played a great match and credit to her," said Jankovic."Overall it was a difficult day, I gave my best but there are a lot of things I could have done better." Errani, 27, was ousted from the semi-finals last year by Victoria Azarenka, who went on to lose last year's final to Williams. But she admitted the home support was so intense she had to concentrate hard. "I've never felt something like the before. The crowd were giving me so much support that it almost put me off," said Errani. Raffaella Reggi was the last Italian woman to win the Italian Open in 1985.