CHENNAI: Opener Murali Vijay cracked a blistering 56-ball century as Chennai Super Kings kept their semi-final hopes alive beating Rajasthan Royals by 23 runs in a high-scoring Indian Premier League match here today. Opting to bat, Chennai rode on Vijay's 127 run knock with a highly challenging 246 —also the highest score in the tournament. Vijay adorned his innings with 11 sixes and eight fours, while Albie Morkel also made a breezy 34-ball 62. The hosts then restricted Rajasthan to 223-5, as opener Naman Ojha's unbeaten 55-ball 94 and Shane Watson's 60 off 25 balls went in vain. Watson, who hit five fours and as many sixes, paired up with Ojha in the middle and the duo added 97 runs for third wicket. But the partnership came to an end just when Doug Bollinger bowled out Watson in the 16th over. In Mohali on Friday, Kevin Pietersen (66 not out) got three lives before notching up his maiden IPL half-century to help Royal Challengers Bangalore score a comprehensive six-wicket victory over Kings XI Punjab. Pietersen palyed sheet anchor with two crucial partnerships -- 71 off 51 balls for the third wicket with Virat Kohli and 40 from just 15 balls for fourth wicket with Robin Uthappa (22) as RCB romped home with five balls to spare in their chase of 182. Earlier, Kumar Sangakkara top-scored with a 27-ball 45 as Kings XI Punjab posted a challenging 181-5 after electing to bat. With the fifth win Bangalore are on second spot with 10 points.