One of the most eagerly-awaited clashes at the World Indoor Athletics Championships will be in the pentathlon between defending champion Jessica Ennis and world heptathlon title-holder Tatyana Chernova. The winner of the gruelling five-discipline event, which includes the 60m hurdles, high jump, shot put, long jump and 800m, on Friday will gain a "massive psychological boost" heading towards the London Olympics, according to Ennis. The Briton, who was unseated by Russian Chernova for silver at last year's gripping world outdoor championships in Daegu, said: "I'm definitely looking forward to it. "The last time we competed against her was in Daegu, so I'm definitely looking forward to that head-to-head again. "It's going to be a massive psychological boost for anyone that does well. "Looking at everyone's performances, that way they're performing around the world at the moment, everyone's on top form, so to come away with this, whether it's a personal best or a win and a medal, that's definitely going to give you a boost going forward for the rest of the year." In terms of scoring, Ennis has an 82-point advantage over Chernova in personal bests, 4,937 to 4,855, with many reckoning that Irina Belova's world record of 4,991 points might tumble here. "Given my shape and the shape the other girls are in, it's going to take a PB to get it but it's something any one of us could achieve," Ennis said. "It's not something I'm focusing on, but it would be a nice bonus," she added when asked whether she would like to break Belova's world record mark. Chernova also warned that while everyone liked to focus on her head-to-head battle with Ennis, there was a very strong field beyond the pair. "It's nice for me and good for this competition to see such a high standard. It should be very interesting," she said. "But you can't forget about the other girls: (Ukraine's reigning Olympic heptathlon champion) Natalya Dobrynska and Ekaterina Bolshova (of Russia, the world leader with a best of 4,896). The winner will be the strongest." Chernova also played down fears that she might be overawed come the London Olympics, when the large part of a capacity stadium will be rooting for Ennis. "My father, my mother and my coach will be there. They believe in me," she simply said, adding that her relationship with the Sheffield-born Ennis was cordial. "Yes, we're friends. We speak between events. But we don't speak about competition. We speak about life, future plans."