Survived 20 Miles Run Saturday

I finished 18 miles last Sunday, and thought it would be
just another 2 miles for the 20 miles run.

Actually it is not, it is much harder.  Compared to the last
long run, First, the average pace is almost the same. But this
run was a little bit faster for the first 9 miles, so I was very
tired during the last a few miles(also after the run).

Here are the splits:

Split	Time	Distance	Avg Pace
Summary	3:15:12.5	20.01	9:45
1	9:18.0	1.00	9:18
2	8:34.3	1.00	8:34
3	8:38.8	1.00	8:39
4	8:33.7	1.00	8:34
5	8:18.4	1.00	8:18
6	8:34.4	1.00	8:34
7	8:56.8	1.00	8:57
8	8:59.7	1.00	9:00
9	9:19.4	1.00	9:19
10	10:42.9	1.00	10:43
11	11:04.7	1.00	11:05
12	9:51.1	1.00	9:51
13	9:32.0	1.00	9:32
14	9:30.3	1.00	9:30
15	9:50.9	1.00	9:51
16	10:41.9	1.00	10:42
17	10:02.3	1.00	10:02
18	10:22.5	1.00	10:23
19	12:35.3	1.00	12:35
20	11:42.1	1.00	11:42
21	:03.2	0.01	8:46

Anyone, I am glad to complete the run within 180 minutes.
(My goal is 10 minutes per mile).