The 42-year-old former Greece and Olympiakos goalkeeper, who was one of Greece's heroes of the Euro 2004 triumph, took over on an interim basis following the sudden departure of Leonardo Jardim on Saturday.
Goals from Algerian striker Rafik Djebbour and winger Djamel Abdoun either side of halftime enabled the hosts to extend their lead at the top over PAOK Salonika to 13 points after the Black and Whites lost 1-0 at Asteras Tripolis the previous day.
"Tonight I had more anxiety to be honest than when I made my debut as a player," Nikopolidis told reporters.
"As a player I have international experience and it was not so difficult to find my feet, but it's a completely different thing to be a coach; nonetheless I think I can do it."
He added he was ready to take on the role on a permanent basis if it was offered to him.
"I remember 10 years ago when I came as a player to the club and I was told in no uncertain terms that there are two hot seats - one is the coach and the other is the goalkeeper," he said.
"Still, I don't know what will happen ... Olympiakos can also search for a coach and the decision will come from the administration and the president."
While unbeaten Olympiakos continue to march on in their bid for a 40th league title, arch rivals Panathinaikos' struggles continued with a disappointing 1-1 draw at home to Panthrakikos on Saturday.
Spanish striker Toche gave the Greens a 74th-minute lead but former Panatha frontman Dimitris Papadopoulos returned to haunt the club with an equaliser five minutes from time to leave Panathinaikos ninth in the table with 22 points from 18 matches.
In Sunday's late game, striker Antonis Petropoulos headed home in the sixth minute of stoppage time to rescue a point for AEK Athens in an ill-tempered 1-1 draw at Aris Salonika in which both teams were reduced to nine men.
The hosts had taken an 84th-minute lead through David Aganzo's close-range effort but Petropoulos, who joined earlier this month from Panathinaikos, scored with a superb diving header to salvage a draw that lifted his side out of the relegation zone.
"It was a match I didn't think that we deserved to lose and I was very disappointed as I thought we'd leave with nothing, but then we got that late goal and the result is such a great boost for us," AEK manager Ewald Lienen told reporters. (Editing by Sonia Oxley)