After all the doubts and frustrations that shrouded his first three races for Williams-Renault, the German began to justify his selection by the champion team with a performance of immense authority and composure in the San Marino Grand Prix. He produced the pace when it mattered to turn the first round of pit stops to his advantage, the aggression to fight off Michael Schumacher, and then the judgment to ensure he beat his compatriot to the line with minimal strain on his equipment.
Down in the team's compound, Frank Williams, who signed Frentzen rather than retain Damon Hill with an eye on the menace of Schumacher in a developing Ferrari, was patently content with his choice. He did not claim vindication, but then he did not have to.
Instead, he said of Frentzen: "He was very impressive. Very strong, but also very smooth and very calm, particularly at the end, when Michael was pushing him hard. He was concerned about his brakes at the end but they were fine and we were telling him to go quicker. But he was in control. This will give him a huge lift."
The more so because the man he ultimately defeated was Schumacher. Jacques Villeneuve, the championship leader, had been forced out of contention by a gear selection problem on his Williams and Eddie Irvine, in third place, was almost a lap down at the wheel of the other Ferrari.
So, it came down to a head-to-head with Schumacher. Since they went their separate ways after driving together in the Mercedes Junior Sportscar team, Schumacher has monopolised the success and acclaim, and even married Frentzen's former girlfriend. Both claimed there was no lingering animosity, but everyone wondered. And they wondered especially in Germany.
The pair almost came into contact early in the race, when Frentzen challenged for second place. Schumacher resisted vigorously. And when Frentzen, to his elation and surprise, emerged from the pits just ahead of the Ferrari, he defended with equal resolve. Again, a collision was averted and they presented Germany with a first one-two finish in a grand prix, just 1.237sec apart.
In any other pair of hands the Ferrari would probably have been nowhere near the winner and might not have been anyway had Villeneuve's car not failed him. Schumacher and the banks of red-clad humanity seemed happy enough and Frentzen, even if he did not look it, assured the world the feeling was "great and fantastic".
Frentzen went on: "I thought Jacques was going to have his first pit stop after me, but when he and Michael went in I put in two quick laps and gained about two seconds. My pit stop was also quick and when I came out and saw P1 (position one) I was absolutely pleased and surprised.
"It was close and I gave Michael a hard time like he gave me. At that stage I was concentrating on getting rid of Michael rather than winning the race. I was really pushing hard to keep my concentration at the end. Many things were in my head. I didn't want my brakes to go as they did in Melbourne and I was also worried because it started raining slightly. And at the same time I was trying to maintain my rhythm.
"But it was my time. I think I will be able to say more about it tomorrow. I can't really remember the last time I won a race. It was nice for me and also for all German motor racing fans."
Schumacher complained he had been held up by back markers and Ferrari's team director, Jean Todt, marched up to the Sauber crew and suggested in blunt terms they get Nicola Larini out of his No1 driver's path. But Schumacher acknowledged the Williams still had the edge and he would have settled for third place before the race. He anticipated better days ahead; and more German dominance.
He said: "When Heinz-Harald came out ahead of me I knew that was it. Those two laps made the difference. He did a fantastic job and finally made it. We had a great fight, very fair. Second is better than I expected.
"It was a great race for the German spectators. This is what they wanted to see. It's great for Germany having three competitive drivers. I don't know what happened to my brother today, but very soon we shall have all three up here."
That is no idle threat. Ralf Schumacher ran a strong fourth early in the race, but a broken drive shaft halted his Jordan-Peugeot after 17 laps. David Coulthard, also, figured prominently and was on course for a place on the podium when the engine of his McLaren-Mercedes failed him.
Chief among the beneficiaries of their misfortune were Giancarlo Fisichella, fourth in the other Jordan, Jean Alesi, fifth in a Benetton-Renault, and Mika Hakkinen, sixth in the other McLaren.
Johnny Herbert, in his 100th grand prix, and Gerhard Berger, in his 200th, had only retirement and disappointment to mark the occasion.
Hill was another on short time, ramming his Arrows- Yamaha into Shinji Nakano's Prost-Mugen-Honda and crippling both cars. Hill claimed, with scant conviction, that the Japanese driver turned into him.
The stewards saw it differently and imposed on Hill a one-race ban suspended for one race. The Englishman's growing frustration may well have been a factor. He had to start in the pit lane in his spare car after a starter motor problem sabotaged his race car and he found progress painstakingly slow.
He said: "We've got to get our act together. I don't enjoy starting last. I was getting held up badly by the guys ahead of me and I could see I was losing time. It was going to be a very difficult job getting a result today anyway. We just have to keep working hard and looking ahead. I have got to think about the next race and forget this one."
You sense, however, there is more anguish to come for the world champion this season.
1 Heinz-Harald Frentzen (Ger) 10pts
(Williams-Renault) 1hr 31min 0.673sec (avge speed 125.215mph/201.509 kph)
2 Michael Schumacher (Ger) 6pts
(Ferrari) at 1.237sec
3 Eddie Irvine (GB) 4pts
(Ferrari) at 1:18.343
4 Giancarlo Fisichella (It) 3pts
(Jordan-Peugeot) at 1:23.388
5 Jean Alesi (Fr) 2pts
(Benetton-Renault) at one lap
6 Mika Hakkinen (Fin) 1pt
(McLaren-Mercedes) at 1 lap
7 Nicola Larini (It) Sauber-Petronas 1 lap; 8 Olivier Panis (Fr) Prost- Mugen-Honda 1 lap; 9 Mika Salo (Fin) Tyrrell 2 laps; 10 Jos Verstappen (Neth) Tyrrell-Ford 2 laps; 11 Ukyo Katayama (Japan) Minardi-Hart 3 laps.
Did not finish (not classified): 12 Pedro Diniz (Bra) Arrows-Yamaha 53 laps completed; 13 Jacques Villeneuve (Can) Williams-Renault 40 laps; 14 David Coulthard (GB) McLaren-Mercedes 38; 15 Rubens Barrichello (Bra) Stewart-Ford 32; 16 Johnny Herbert (GB) Sauber-Petronas 18; 17 Ralf Schumacher (Ger) Jordan-Peugeot 17; 18 Shinji Nakano (Japan) Prost-Mugen-Honda 11; 19 Damon Hill (GB) Arrows-Yamaha 11; 20 Gerhard Berger (Aut) Benetton- Renault 4; 21 Jan Magnussen (Den) Stewart-Ford 2.
Did not start (failed to complete lap): 22 Jarno Trulli (It) Minardi- Hart.
Fastest lap: Frentzen 1:25.531 (128.939mph/ 207.503 kph).