MAURITIUS 8 May 2015 (AFP) - Olesen, who won a second European Tour title in Perth at the end of last season but has started just four times on the 2015 Race to Dubai, started the day as one of three co-leaders on six under par.
Having seen Swede Pelle Edberg set the clubhouse mark at eight under in the morning session, Olesen was pegged back when he bogeyed the first and third holes.
But five birdies in the next six holes, culminating in efforts from 20 feet at the eighth and 12 feet at the ninth, allowed the Dane to reach the turn in 32.
A bogey at the 13th briefly checked his progress, but Olesen birdied the 16th from five feet and saved par with a clutch ten footer at the 17th.
At nine under Olesen leads Sweden’s Edberg by a single shot with England’s Matt Fitzpatrick and South Africans Thomas Aiken and Dean Burmester tied for third on seven under.
"On the front nine it was quite tricky but I kept it going out there and finished strongly with birdies on seven, eight and nine and then tried to keep fighting," Olesen said.
"I’m enjoying being out there and I holed some nice putts. All in all it was a good day and I’m happy with three under.
"I’m really looking forward to the weekend. It’s been a long break and then all of a sudden I’m up there in the lead, so it will be a lot of fun. Mauritius is a beautiful country, so no matter what happens, I will still like it."
Leading scores on Friday in the second round of the Mauritius Open, counting toward the European PGA Tour:
133 - Thorbjorn Olesen (DEN) 65-68
134 - Pelle Edberg (SWE) 68-66
135 - Thomas Aiken (RSA) 69-66, Dean Burmester (RSA) 67-68, Matthew Fitzpatrick (ENG) 68-67
137 - Terry Pilkadiris (AUS) 66-71, John Parry (ENG) 67-70, Oliver Bekker (RSA) 66-71, George Coetzee (RSA) 70-67, Rahil Gangjee (IND) 67-70, Masahiro Kawamura (JPN) 68-69, Wang Jeung-Hun (KOR) 65-72, Carlos Pigem (ESP) 65-72
138 - Scott Hend (AUS) 72-66, Pablo Martín (ESP) 72-66, Daniel Chopra (SWE) 70-68, Andrew McArthur (SCO) 68-70, Mardan Mamat (SIN) 69-69, Colin Nel (RSA) 69-69
139 - Mikael Lundberg (SWE) 68-71, Steve Lewton (ENG) 70-69, Kalem Richardson (AUS) 73-66, Sam Brazel (AUS) 69-70, Keith Horne (RSA) 70-69, Paul Peterson (USA) 69-70, Tiaart Van der Walt (RSA) Vart (NED) 73-66, Jazz Janewattananond (THA) 69-70