THE acrimonous relationship between Ayrton Senna and Michael Schumacher deteriorated further after a testing session for the German Grand Prix at Hockenheim yesterday. Senna, accusing the Benetton-Ford driver of endangering him by blocking his way on the track, seized Schumacher by the collar of his overalls on the German's return to the pits.

Explaining his driving tactics, Schumacher reasoned that he saw the McLaren-Honda driver in his rear-view mirror but thought the Brazilian was going too slowly and maintained his line. Schumacher added that he had already made peace with Senna, although this was not confirmed by the three- times world champion.

The incident is not the first between the Formula One rivals. After the Brazilian Grand Prix in April, Schumacher expressed his displeasure with the champion's driving tactics. He accused Senna of 'playing around' as he attempted to overtake - an accusation made in public and to the astonishment of the two other drivers on the podium - Nigel Mansell and Riccardo Patrese.

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Senna later explained that he had an engine problem and that his change of pace was not deliberate. He reprimanded the German, saying he should have checked his facts.

Earlier this month, Senna was shunted out of the French Grand Prix on the first lap by Schumacher. Senna later confronted Schumacher who accepted responsibility for the incident.

In the 1987 Belgian Grand Prix, Senna was involved in an accident with Nigel Mansell. Both went off the track and Mansell later grabbed Senna by the throat and had to be restrained by Lotus mechanics.

Schumacher and Senna were among a number of drivers at Hockenheim yesterday on the second day of a practice session for the German Grand Prix on 26 July. Mansell, the clear leader in the drivers' championship, had a best lap of 1min 40.38sec on the same track where Senna was involved in a serious accident in testing last year.

Patrese, Mansell's Williams-Renault team-mate, was second-quickest, recording a time of 1:40.81 while Schumacher was third with 1:41.96. Senna's time of 1:43.71 was the seventh-fastest of the day.

Schumacher is third in the Formula One world championship after nine races this season, while Senna, the defending champion, is in fifth place. Both, however, have been left in the exhaust of Mansell, who appears to heading for his first championship after seven wins and one second place finish this year.