Federer, showing flashes of brilliance mixed with occasional errors, closed out the second-round match in just over an hour as he triumphed 6-2 7-5 against the Finn.
The 17-time Grand Slam winner was making his first appearance in Turkey with the Istanbul Open the first ATP world tour event to be played in the country.
Federer raced through the first set in just 20 minutes, pulling out his full armoury of drop shots, cross-court forehands and backhand winners against a clearly hesitant Nieminen, the world 71.
A stunning drop shot from Federer that fell dead inside the service court broke Nieminen’s serve in the fifth game and left the crowd gasping.??
The crowd, who had braved heavy evening traffic to catch Federer play at the 8,000-capacity Garanti Koza Arena on the outskirts of Istanbul, began to get behind the Finn to prolong the game.
Nieminen showed greater confidence in the second set, holding his serve with ease as an over-relaxed Federer sprayed the ball wide regularly.
The Federer forehand was responsible for a string of unforced errors, allowing Nieminen to hold serve without trouble.
But Federer, serving and volleying on occasion and delivering nine aces in the match, found his top gear at the close of the set.
Piling pressure on the Nieminen second serve and using his trademark drive volley to great effect, Federer finally broke Nieminen to lead 6-5.
He then served out to love, finishing with a stunning backhand cross court that left Nieminen with arms and legs akimbo.
In Friday’s quarter-finals, Federer will face Daniel Gimeno-Traver of Spain who overcame Kazakhstan’s Mikhail Kukushkin in straight sets.
Federer, who is seeded to meet world No 11 Grigor Dimitrov of Bulgaria in the final, is hoping to use the clay-court event to fine tune his bid for a second French Open title next month.??
He is looking for confidence on the slower clay, after a long hard-court season, having lost in the third round on clay to Gael Monfils at the Monte Carlo Masters this month.