McLaren drivers set three of the five quickest times in Friday practice at the Canadian Grand Prix.
Alonso was the fastest race driver in Friday practice
Test driver Pedro de la Rosa was fastest with a time of one minute 14.662 seconds, beating his Toyota counterpart Ricardo Zonta by 0.196secs.
Renault's world championship leader Fernando Alonso was the fastest race driver, ahead of McLaren's Kimi Raikkonen and Juan Pablo Montoya.
World champion Michael Schumacher could manage only 16th place for Ferrari.
Schumacher has won in Canada more times than any other driver, and if he breaks his winless start to the season would become the first man in history to win an event eight times.
But Alonso's team-mate Giancarlo Fisichella said Schumacher had no chance of winning this weekend.
"I was behind him (Schumacher) on the long runs, I was catching him and I was about a second quicker a lap," Fisichella said after the Friday's second practice session.
"When I was behind him he was struggling with the grip on the rear end, in braking he was not so aggressive and even into the corner wasn't quick enough.
"So I think Ferrari are still struggling here. That's not bad news for us.
"Even a seven-times world champion like Michael, who is a great driver, if he hasn't got a competitive car cannot fight for the podium."
Schumacher agreed, saying: "We are not looking too competitive here, looking at the lap times."
Fisichella predicted another battle between McLaren and Renault, while Alonso said he felt McLaren would retain the edge on pace they have shown since the San Marino Grand Prix in April.
Alonso said: "I think they (McLaren) are a little bit stronger than us... but here it will be very close between the two teams I hope."
Schumacher and Ferrari are struggling
American Scott Speed, making his debut at a Grand Prix for Red Bull, started well in the first session by lapping faster than race drivers David Coulthard and Christian Klien.
But he blotted his copybook in the second when he spun and stalled at Turn Four, ending his session early.
Follow the Canadian Grand Prix live on the BBC Sport website. Qualifying is at 1800 BST on Saturday, with the race at the same time on Sunday.
Fastest times from Friday practice at the Canadian Grand Prix:
1 Pedro de la Rosa (Spa)* McLaren-Mercedes one minute 14.662 seconds
2 Ricardo Zonta (Brz)* Toyota 1:14.858
3 Fernando Alonso (Spa) Renault 1:15.376
4 Juan Pablo Montoya (Col) McLaren-Mercedes 1:15.625
5 Kimi Raikkonen (Fin) McLaren-Mercedes 1:15.679
6 Giancarlo Fisichella (Ita) Renault 1:15.846
7 Jenson Button (Britain) BAR-Honda 1:16.190
8 Takuma Sato (Jpn) BAR-Honda 1:16.313
9 Ralf Schumacher (Ger) Toyota 1:16.364
10 Rubens Barrichello (Brz) Ferrari 1:16.459
11 Jarno Trulli (Ita) Toyota 1:16.638
12 Mark Webber (Aus) Williams-BMW 1:16.661
13 Jacques Villeneuve (Can) Sauber-Petronas 1:16.718
14 Felipe Massa (Brz) Sauber-Petronas 1:16.727
15 Nick Heidfeld (Ger) Williams-BMW 1:16.826
16 Michael Schumacher (Ger) Ferrari 1:16.872
17 David Coulthard (GB) Red Bull 1:17.299
18 Christian Klien (Aut) Red Bull 1:17.922
19. Patrick Friesacher (Austria) Minardi 1:18.115
20 Narain Karthikeyan (Ind) Jordan 1:18.234
21 Christijan Albers (Ned) Minardi 1:18.463
22 Tiago Monteiro (Por) Jordan 1:19.186
23 Scott Speed (USA)* Red Bull 1:19.270
* = Driver not eligible to race