I want to add an additional time of '10:01' for J Petry to the following list: 

```
PlayerMatrix = [["['J. Petry', '24:17']"], ["['G. Chase', '11:03']"]]

```

so I want to get output of ......

```
PlayerMatrix = [["['J. Petry', '24:17', '10:01']"], ["['G. Chase', '11:03']"]]

```

I've tried 

```
PlayerMatrix[0].append("10:01")

```

and this gives me.......

```
PlayerMatrix = [["['J. Petry', '24:17']", '10:01'], ["['G. Chase', '11:03']"]]

```

ie instead of adding it to the first list it creates a second list. There must be something simple I'm doing wrong.....